diff --git a/modtools/change-build-menu.lua b/modtools/change-build-menu.lua
new file mode 100644
index 0000000000..8144a13bfe
--- /dev/null
+++ b/modtools/change-build-menu.lua
@@ -0,0 +1,563 @@
+-- Edit the build mode sidebar menus.
+--
+-- Based on my script for the Rubble addon "Libs/Change Build List".
+
+--[[
+Copyright 2016 Milo Christiansen
+
+This software is provided 'as-is', without any express or implied warranty. In
+no event will the authors be held liable for any damages arising from the use of
+this software.
+
+Permission is granted to anyone to use this software for any purpose, including
+commercial applications, and to alter it and redistribute it freely, subject to
+the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim
+that you wrote the original software. If you use this software in a product, an
+acknowledgment in the product documentation would be appreciated but is not
+required.
+
+2. Altered source versions must be plainly marked as such, and must not be
+misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source distribution.
+]]
+
+--@ module = true
+--@ enable = true
+
+local usage = [====[
+modtools/change-build-menu
+==========================
+
+Change the build sidebar menus.
+
+This script provides a flexible and comprehensive system for adding and removing
+items from the build sidebar menus. You can add or remove workshops/furnaces by
+text ID, or you can add/remove ANY building via a numeric building ID triplet.
+
+Changes made with this script do not survive a save/load. You will need to redo
+your changes each time the world loads.
+
+Just to be clear: You CANNOT use this script AT ALL if there is no world
+loaded!
+
+* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+
+Usage:
+
+modtools/change-build-menu start|enable
+enable modtools/change-build-menu
+    Start the ticker. This needs to be done before any changes will take
+    effect. Note that you can make changes before or after starting the
+    ticker, both options should work equally well.
+
+modtools/change-build-menu stop|disable
+disable modtools/change-build-menu
+    Stop the ticker. Does not clear stored changes. The ticker will
+    automatically stop when the current world is unloaded.
+
+modtools/change-build-menu add <ID> <CATEGORY> [<KEY>]
+    Add the workshop or furnace with the ID <ID> to <CATEGORY>.
+    <KEY> is an optional DF hotkey ID.
+
+    <CATEGORY> may be one of:
+        MAIN_PAGE
+        SIEGE_ENGINES
+        TRAPS
+        WORKSHOPS
+        FURNACES
+        CONSTRUCTIONS
+        MACHINES
+        CONSTRUCTIONS_TRACK
+
+    Valid <ID> values for hardcoded buildings are as follows:
+        CARPENTERS
+        FARMERS
+        MASONS
+        CRAFTSDWARFS
+        JEWELERS
+        METALSMITHSFORGE
+        MAGMAFORGE
+        BOWYERS
+        MECHANICS
+        SIEGE
+        BUTCHERS
+        LEATHERWORKS
+        TANNERS
+        CLOTHIERS
+        FISHERY
+        STILL
+        LOOM
+        QUERN
+        KENNELS
+        ASHERY
+        KITCHEN
+        DYERS
+        TOOL
+        MILLSTONE
+        WOOD_FURNACE
+        SMELTER
+        GLASS_FURNACE
+        MAGMA_SMELTER
+        MAGMA_GLASS_FURNACE
+        MAGMA_KILN
+        KILN
+
+modtools/change-build-menu remove <ID> <CATEGORY>
+    Remove the workshop or furnace with the ID <ID> from <CATEGORY>.
+
+    <CATEGORY> and <ID> may have the same values as for the "add" option.
+
+modtools/change-build-menu revert <ID> <CATEGORY>
+    Revert an earlier remove or add operation. It is NOT safe to "remove"
+    an "add"ed building or vice versa, use this option to reverse any
+    changes you no longer want/need.
+
+* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+
+Module Usage:
+
+To use this script as a module put the following somewhere in your own script:
+
+    local buildmenu = reqscript "change-build-menu"
+
+Then you can call the functions documented here like so:
+
+    -- Example: Remove the carpenters workshop.
+    buildmenu.ChangeBuilding("CARPENTERS", "WORKSHOPS", false)
+
+    -- Make it impossible to build walls (not recommended!).
+    local typ, styp = df.building_type.Construction, df.construction_type.Wall
+    buildmenu.ChangeBuildingAdv(typ, styp, -1, "CONSTRUCTIONS", false)
+
+Note that to allow any of your changes to take effect you need to start the
+ticker. See the "Command Usage" section.
+
+Global Functions:
+
+function GetWShopID(btype, bsubtype, bcustom)
+    GetWShopID returns a workshop's or furnace's string ID based on its
+    numeric ID triplet. This string ID *should* match what is expected
+    by eventful for hardcoded buildings.
+
+function GetWShopType(id)
+    GetWShopIDs returns a workshop or furnace's ID numbers as a table.
+    The passed in ID should be the building's string identifier, it makes
+    no difference if it is a custom building or a hardcoded one.
+    The return table is structured like so: `{type, subtype, custom}`
+
+function IsEntityPermitted(id)
+    IsEntityPermitted returns true if DF would normally allow you to build
+    a workshop or furnace. Use this if you want to change a building, but
+    only if it is permitted in the current entity. You do not need to
+    specify an entity, the current fortress race is used.
+
+ChangeBuilding(id, category, [add, [key]])
+ChangeBuildingAdv(typ, subtyp, custom, category, [add, [key]])
+    These two functions apply changes to the build sidebar menus. If "add"
+    is true then the building is added to the specified category, else it
+    is removed. When adding you may specify "key", a string DF hotkey ID.
+
+    The first version of this function takes a workshop or furnace ID as a
+    string, the second takes a numeric ID triplet (which can specify any
+    building, not just workshops or furnaces).
+
+function RevertBuildingChanges(id, category)
+function RevertBuildingChangesAdv(typ, subtyp, custom, category)
+    These two functions revert changes made by "ChangeBuilding" and
+    "ChangeBuildingAdv". Like those two functions there are two versions,
+    a simple one that takes a string ID and one that takes a numeric ID
+    triplet.
+]====]
+
+-- From here until I say otherwise the APIs are generic building manipulation functions from "Libs/Buildings"
+
+local utils = require "utils"
+
+local wshop_type_to_id = {
+    [df.workshop_type.Carpenters] = "CARPENTERS",
+    [df.workshop_type.Farmers] = "FARMERS",
+    [df.workshop_type.Masons] = "MASONS",
+    [df.workshop_type.Craftsdwarfs] = "CRAFTSDWARFS",
+    [df.workshop_type.Jewelers] = "JEWELERS",
+    [df.workshop_type.MetalsmithsForge] = "METALSMITHSFORGE",
+    [df.workshop_type.MagmaForge] = "MAGMAFORGE",
+    [df.workshop_type.Bowyers] = "BOWYERS",
+    [df.workshop_type.Mechanics] = "MECHANICS",
+    [df.workshop_type.Siege] = "SIEGE",
+    [df.workshop_type.Butchers] = "BUTCHERS",
+    [df.workshop_type.Leatherworks] = "LEATHERWORKS",
+    [df.workshop_type.Tanners] = "TANNERS",
+    [df.workshop_type.Clothiers] = "CLOTHIERS",
+    [df.workshop_type.Fishery] = "FISHERY",
+    [df.workshop_type.Still] = "STILL",
+    [df.workshop_type.Loom] = "LOOM",
+    [df.workshop_type.Quern] = "QUERN",
+    [df.workshop_type.Kennels] = "KENNELS",
+    [df.workshop_type.Ashery] = "ASHERY",
+    [df.workshop_type.Kitchen] = "KITCHEN",
+    [df.workshop_type.Dyers] = "DYERS",
+    [df.workshop_type.Tool] = "TOOL",
+    [df.workshop_type.Millstone] = "MILLSTONE",
+}
+local wshop_id_to_type = utils.invert(wshop_type_to_id)
+
+local furnace_type_to_id = {
+    [df.furnace_type.WoodFurnace] = "WOOD_FURNACE",
+    [df.furnace_type.Smelter] = "SMELTER",
+    [df.furnace_type.GlassFurnace] = "GLASS_FURNACE",
+    [df.furnace_type.MagmaSmelter] = "MAGMA_SMELTER",
+    [df.furnace_type.MagmaGlassFurnace] = "MAGMA_GLASS_FURNACE",
+    [df.furnace_type.MagmaKiln] = "MAGMA_KILN",
+    [df.furnace_type.Kiln] = "KILN",
+}
+local furnace_id_to_type = utils.invert(furnace_type_to_id)
+
+-- GetWShopID returns a workshop or furnace's string ID based on it's numeric ID triplet.
+-- This string ID *should* match what is expected by eventful for hardcoded buildings.
+function GetWShopID(btype, bsubtype, bcustom)
+    if btype == df.building_type.Workshop then
+        if wshop_type_to_id[bsubtype] ~= nil then
+            return wshop_type_to_id[bsubtype]
+        else
+            return df.building_def_workshopst.find(bcustom).code
+        end
+    elseif btype == df.building_type.Furnace then
+        if furnace_type_to_id[bsubtype] ~= nil then
+            return furnace_type_to_id[bsubtype]
+        else
+            return df.building_def_furnacest.find(bcustom).code
+        end
+    end
+end
+
+-- GetWShopIDs returns a workshop or furnace's ID numbers as a table.
+-- The passed in ID should be the building's string identifier, it makes
+-- no difference if it is a custom building or a hardcoded one.
+-- The return table is structured like so: `{type, subtype, custom}`
+function GetWShopType(id)
+    if wshop_id_to_type[id] ~= nil then
+        -- Hardcoded workshop
+        return {
+            type = df.building_type.Workshop,
+            subtype = wshop_id_to_type[id],
+            custom = -1,
+        }
+    elseif furnace_id_to_type[id] ~= nil then
+        -- Hardcoded furnace
+        return {
+            type = df.building_type.Furnace,
+            subtype = furnace_id_to_type[id],
+            custom = -1,
+        }
+    else
+        -- User defined workshop or furnace.
+        for i, def in ipairs(df.global.world.raws.buildings.all) do
+            if def.code == id then
+                local typ = df.building_type.Furnace
+                local styp = df.furnace_type.Custom
+                if getmetatable(def) == "building_def_workshopst" then
+                    typ = df.building_type.Workshop
+                    styp = df.workshop_type.Custom
+                end
+
+                return {
+                    type = typ,
+                    subtype = styp,
+                    custom = i,
+                }
+            end
+        end
+    end
+    return nil
+end
+
+-- OK, Now to "Libs/Change Build List" proper...
+
+--[[
+    -- Examples:
+
+    -- Remove the carpenters workshop.
+    ChangeBuilding("CARPENTERS", "WORKSHOPS", false)
+
+    -- Make it impossible to build walls (not recommended!).
+    ChangeBuildingAdv(df.building_type.Construction, df.construction_type.Wall, -1, "CONSTRUCTIONS", false)
+
+    -- Add the mechanic's workshops to the machines category.
+    ChangeBuilding("MECHANICS", "MACHINES", true, "CUSTOM_E")
+]]
+
+local category_name_to_id = {
+    ["MAIN_PAGE"] = 0,
+    ["SIEGE_ENGINES"] = 1,
+    ["TRAPS"] = 2,
+    ["WORKSHOPS"] = 3,
+    ["FURNACES"] = 4,
+    ["CONSTRUCTIONS"] = 5,
+    ["MACHINES"] = 6,
+    ["CONSTRUCTIONS_TRACK"] = 7,
+}
+
+--[[
+    {
+        category = 0, -- The menu category id (from category_name_to_id)
+        add = true, -- Are we adding a workshop or removing one?
+        id = {
+            -- The building IDs.
+            type = 0,
+            subtype = 0,
+            custom = 0,
+        },
+    }
+]]
+stuffToChange = stuffToChange or {}
+
+-- Returns true if DF would normally allow you to build a workshop or furnace.
+-- Use this if you want to change a building, but only if it is permitted in the current entity.
+function IsEntityPermitted(id)
+    local wshop = GetWShopType(id)
+
+    -- It's hard coded, so yes, of course it's permitted, why did you even ask?
+    if wshop.custom == -1 then
+        return true
+    end
+
+    local entsrc = df.historical_entity.find(df.global.ui.civ_id)
+    if entsrc == nil then
+        return false
+    end
+    local entity = entsrc.entity_raw
+
+    for _, bid in ipairs(entity.workshops.permitted_building_id) do
+        if wshop.custom == bid then
+            return true
+        end
+    end
+    return false
+end
+
+function RevertBuildingChanges(id, category)
+    local wshop = GetWShopType(id)
+    if wshop == nil then
+        qerror("RevertBuildingChanges: Invalid workshop ID: "..id)
+    end
+
+    RevertBuildingChangesAdv(wshop.type, wshop.subtype, wshop.custom, category)
+end
+
+function RevertBuildingChangesAdv(typ, subtyp, custom, category)
+    local cat
+    if tonumber(category) ~= nil then
+        cat = tonumber(category)
+    else
+        cat = category_name_to_id[category]
+        if cat == nil then
+            qerror("ChangeBuilding: Invalid category ID: "..category)
+        end
+    end
+
+    for i = #stuffToChange, 1, -1 do
+        local change = stuffToChange[i]
+        if change.category == cat then
+            if typ == change.id.type and subtyp == change.id.subtype and custom == change.id.custom then
+                table.remove(stuffToChange, i)
+            end
+        end
+    end
+end
+
+function ChangeBuilding(id, category, add, key)
+    local cat
+    if tonumber(category) ~= nil then
+        cat = tonumber(category)
+    else
+        cat = category_name_to_id[category]
+        if cat == nil then
+            qerror("ChangeBuilding: Invalid category ID: "..category)
+        end
+    end
+
+    local wshop = GetWShopType(id)
+    if wshop == nil then
+        qerror("ChangeBuilding: Invalid workshop ID: "..id)
+    end
+
+    if tonumber(key) == nil then
+        key = df.interface_key[key]
+    end
+    if key == nil then
+        key = 0
+    end
+
+    ChangeBuildingAdv(wshop.type, wshop.subtype, wshop.custom, category, add, key)
+end
+
+function ChangeBuildingAdv(typ, subtyp, custom, category, add, key)
+    local cat
+    if tonumber(category) ~= nil then
+        cat = tonumber(category)
+    else
+        cat = category_name_to_id[category]
+        if cat == nil then
+            qerror("ChangeBuilding: Invalid category ID: "..category)
+        end
+    end
+
+    if tonumber(key) == nil then
+        key = df.interface_key[key]
+    end
+    if key == nil then
+        key = 0
+    end
+
+    table.insert(stuffToChange, {
+        category = cat,
+        add = add,
+        key = key,
+        id = {
+            type = typ,
+            subtype = subtyp,
+            custom = custom,
+        },
+    })
+end
+
+-- Return early if module mode. Note that the ticker will not start in module mode!
+-- To start the ticker you need to enable the script first ("enable modtools/change-build-menu").
+if moduleMode then return end
+
+if not dfhack.isWorldLoaded() then
+    dfhack.printerr("change-build-menu: No World Loaded!")
+    dfhack.print(usage)
+    return
+end
+
+args = {...}
+if dfhack_flags and dfhack_flags.enable then
+    table.insert(args, dfhack_flags.enable_state and 'enable' or 'disable')
+end
+
+tickerOn = tickerOn or false
+tickerStart = false
+
+if #args >= 1 then
+    if args[1] == 'start' or args[1] == 'enable' then
+        if not tickerOn then tickerStart = true end
+    elseif args[1] == 'stop' or args[1] == 'disable' then
+        tickerOn = false
+    elseif args[1] == 'add' then
+        ChangeBuilding(args[2], args[3], true, args[4])
+        return
+    elseif args[1] == 'remove' then
+        ChangeBuilding(args[2], args[3], false)
+        return
+    elseif args[1] == 'revert' then
+        RevertBuildingChanges(args[2], args[3])
+        return
+    else
+        dfhack.print(usage)
+        return
+    end
+else
+    dfhack.print(usage)
+    return
+end
+
+-- These two store the values we *think* are in effect, they are used to detect changes.
+sidebarLastCat = sidebarLastCat or -1
+sidebarIsBuild = sidebarIsBuild or false
+
+local function checkSidebar()
+    -- Needs to be "frames" so it ticks over while paused.
+    if tickerOn then
+        dfhack.timeout(1, "frames", checkSidebar)
+    end
+
+    local sidebar = df.global.ui_sidebar_menus.building
+
+    if not sidebarIsBuild and df.global.ui.main.mode ~= df.ui_sidebar_mode.Build then
+        -- Not in build mode.
+        return
+    elseif sidebarIsBuild and df.global.ui.main.mode ~= df.ui_sidebar_mode.Build then
+        -- Just exited build mode
+        sidebarIsBuild = false
+        sidebarLastCat = -1
+        return
+    elseif sidebarIsBuild and sidebar.category_id == sidebarLastCat then
+        -- In build mode, but category has not changed since last frame.
+        return
+    end
+    -- Either we just entered build mode or the category has changed.
+    sidebarIsBuild = true
+    sidebarLastCat = sidebar.category_id
+
+    -- Changes made here do not persist, they need to be made every time the side bar is shown.
+    -- Will just deleting stuff cause a memory leak? (probably, but how can it be avoided?)
+
+    local stufftoremove = {}
+    local stufftoadd = {}
+    for i, btn in ipairs(sidebar.choices_all) do
+        if getmetatable(btn) == "interface_button_construction_building_selectorst" then
+            for _, change in ipairs(stuffToChange) do
+                if not change.add and sidebar.category_id == change.category and
+                btn.building_type == change.id.type and btn.building_subtype == change.id.subtype and
+                btn.custom_type == change.id.custom then
+                    table.insert(stufftoremove, i)
+                end
+            end
+        end
+    end
+    for _, change in ipairs(stuffToChange) do
+        if sidebar.category_id == change.category and change.add then
+            table.insert(stufftoadd, change)
+        end
+    end
+
+    -- Do the actual adding and removing.
+    -- We need to iterate the list backwards to keep from invalidating the stored indexes.
+    for x = #stufftoremove, 1, -1 do
+        -- AFAIK item indexes always match (except for one extra item at the end of "choices_all").
+        local i = stufftoremove[x]
+        sidebar.choices_visible:erase(i)
+        sidebar.choices_all:erase(i)
+    end
+    for _, change in ipairs(stufftoadd) do
+        local button = df.interface_button_construction_building_selectorst:new()
+        button.hotkey_id = change.key
+        button.building_type = change.id.type
+        button.building_subtype = change.id.subtype
+        button.custom_type = change.id.custom
+
+        local last = #sidebar.choices_visible
+        sidebar.choices_visible:insert(last, button)
+        sidebar.choices_all:insert(last, button)
+    end
+end
+
+-- The logic for the ticker is much more complicated here than the Rubble version.
+-- The Rubble version can lean on the script loader, this has to do all the work itself.
+-- Greatly complicating things is that Rubble will only evaluate a module once, whereas a
+-- command script may be evaluated many times.
+
+dfhack.onStateChange.ChangeBuildList = function(event)
+    if event == SC_WORLD_LOADED and not tickerOn and tickerStart then
+        -- Set ticker flags...
+        tickerOn = true
+        tickerStart = false
+
+        -- Then start the ticker itself.
+        checkSidebar()
+    end
+    if event == SC_WORLD_UNLOADED and tickerOn then
+        -- This will kill the ticker next frame.
+        tickerOn = false
+
+        -- The Rubble version doesn't need to worry about this stuff, but we do here...
+        sidebarLastCat = -1
+        sidebarIsBuild = false
+        stuffToChange = nil
+    end
+end
+dfhack.onStateChange.ChangeBuildList(SC_WORLD_LOADED)
diff --git a/modtools/if-entity.lua b/modtools/if-entity.lua
new file mode 100644
index 0000000000..8c8a9566c4
--- /dev/null
+++ b/modtools/if-entity.lua
@@ -0,0 +1,58 @@
+-- Run a command if the current entity matches a given ID.
+
+--[[
+Consider this public domain (CC0).
+    - Milo Christiansen
+]]
+
+local usage = [====[
+modtools/if-entity
+==================
+
+Run a command if the current entity matches a given ID.
+
+To use this script effectively it needs to be called from "raw/onload.init".
+Calling this from the main dfhack.init file will do nothing, as no world has
+been loaded yet.
+
+Usage:
+
+-id
+    Specify the entity ID to match
+-cmd [ commandStrs ]
+    Specify the command to be run if the current entity matches the entity
+    given via -id
+
+All arguments are required.
+
+Example:
+
+    # Print a message if you load an elf fort, but not a dwarf, human, etc
+    # fort.
+    if-entity -id "FOREST" -cmd [ lua "print('Dirty hippies.')" ]
+]====]
+
+local utils = require 'utils'
+
+validArgs = validArgs or utils.invert({
+    'help',
+    'id',
+    'cmd',
+})
+
+local args = utils.processArgs({...}, validArgs)
+
+if not args.id or not args.cmd or args.help then
+    dfhack.print(usage)
+    return
+end
+
+local entsrc = df.historical_entity.find(df.global.ui.civ_id)
+if entsrc == nil then
+    dfhack.printerr("Could not find current entity. No world loaded?")
+    return
+end
+
+if entsrc.entity_raw.code == args.id then
+    dfhack.run_command(table.unpack(args.cmd))
+end