How do I get the weld to work when I move an object from Lighting?

This is a pretty simple process. Once you're done making your model, do the following steps:

1 - Make a part sized 1x1x1

2 - Properties > Surface > FrontSurface > Hinge (The yellow cylinder will be the side the tool will be facing.)

3 - Center your tool, and position it within the center of the part

5 - Put the following script in your tool:

local NEVER_BREAK_JOINTS = false 


local function CallOnChildren(Instance, FunctionToCall) 

    FunctionToCall(Instance)

    for _, Child in next, Instance:GetChildren() do
        CallOnChildren(Child, FunctionToCall)
    end
end

local function GetNearestParent(Instance, ClassName)

    local Ancestor = Instance
    repeat
        Ancestor = Ancestor.Parent
        if Ancestor == nil then
            return nil
        end
    until Ancestor:IsA(ClassName)

    return Ancestor
end

local function GetBricks(StartInstance)
    local List = {}


    CallOnChildren(StartInstance, function(Item)
        if Item:IsA("BasePart") then
            List[#List+1] = Item;
        end
    end)

    return List
end

local function Modify(Instance, Values)

    assert(type(Values) == "table", "Values is not a table");

    for Index, Value in next, Values do
        if type(Index) == "number" then
            Value.Parent = Instance
        else
            Instance[Index] = Value
        end
    end
    return Instance
end

local function Make(ClassType, Properties)

    return Modify(Instance.new(ClassType), Properties)
end

local Surfaces = {"TopSurface", "BottomSurface", "LeftSurface", "RightSurface", "FrontSurface", "BackSurface"}
local HingSurfaces = {"Hinge", "Motor", "SteppingMotor"}

local function HasWheelJoint(Part)
    for _, SurfaceName in pairs(Surfaces) do
        for _, HingSurfaceName in pairs(HingSurfaces) do
            if Part[SurfaceName].Name == HingSurfaceName then
                return true
            end
        end
    end

    return false
end

local function ShouldBreakJoints(Part) 

    if NEVER_BREAK_JOINTS then
        return false
    end

    if HasWheelJoint(Part) then
        return false
    end

    local Connected = Part:GetConnectedParts()

    if #Connected == 1 then
        return false
    end

    for _, Item in pairs(Connected) do
        if HasWheelJoint(Item) then
            return false
        elseif not Item:IsDescendantOf(script.Parent) then
            return false
        end
    end

    return true
end

local function WeldTogether(Part0, Part1, JointType, WeldParent)

    JointType = JointType or "Weld"
    local RelativeValue = Part1:FindFirstChild("qRelativeCFrameWeldValue")

    local NewWeld = Part1:FindFirstChild("qCFrameWeldThingy") or Instance.new(JointType)
    Modify(NewWeld, {
        Name = "qCFrameWeldThingy";
        Part0  = Part0;
        Part1  = Part1;
        C0     = CFrame.new();
        C1     = RelativeValue and RelativeValue.Value or Part1.CFrame:toObjectSpace(Part0.CFrame); 
        Parent = Part1;
    })

    if not RelativeValue then
        RelativeValue = Make("CFrameValue", {
            Parent     = Part1;
            Name       = "qRelativeCFrameWeldValue";
            Archivable = true;
            Value      = NewWeld.C1;
        })
    end

    return NewWeld
end

local function WeldParts(Parts, MainPart, JointType, DoNotUnanchor)

    for _, Part in pairs(Parts) do
        if ShouldBreakJoints(Part) then
            Part:BreakJoints()
        end
    end

    for _, Part in pairs(Parts) do
        if Part ~= MainPart then
            WeldTogether(MainPart, Part, JointType, MainPart)
        end
    end

    if not DoNotUnanchor then
        for _, Part in pairs(Parts) do
            Part.Anchored = false
        end
        MainPart.Anchored = false
    end
end

local function PerfectionWeld() 
    local Tool = GetNearestParent(script, "Tool")

    local Parts = GetBricks(script.Parent)
    local PrimaryPart = Tool and Tool:FindFirstChild("Handle") and Tool.Handle:IsA("BasePart") and Tool.Handle or script.Parent:IsA("Model") and script.Parent.PrimaryPart or Parts[1]

    if PrimaryPart then
        WeldParts(Parts, PrimaryPart, "Weld", false)
    else
        warn("qWeld - Unable to weld part")
    end

    return Tool
end

local Tool = PerfectionWeld()


if Tool and script.ClassName == "Script" then

    script.Parent.AncestryChanged:connect(function()
        PerfectionWeld()
    end)
end