Mirror script

local function reflectOne(part, mirror, mod)

    local x,y,z,r00,r01,r02,r10,r11,r12,r20,r21,r22 = mirror.CFrame:toObjectSpace(part.CFrame):components()

    local mpart = part:Clone()

    mpart.CFrame = mirror.CFrame:toWorldSpace(CFrame.new(-x,y,z,r00,-r01,-r02,-r10,r11,r12,-r20,r21,r22))

    -- CornerWedgeParts are not symmetric so we rotate 90 degrees about
    -- the y axis and exchange the x and z sizes.  (Currently only works
    -- right with integer sized parts since we cannot script other resolutions.)
    if part.className == "CornerWedgePart" then

        mpart.Size = Vector3.new(mpart.Size.z, mpart.Size.y, mpart.Size.x)
        mpart.CFrame = mpart.CFrame * CFrame.Angles(0,math.rad(90),0)
    end

    mpart.Parent = mod
end

------------------------------------------------------------
-- Clone and reflect all Parts and WedgeParts in everything in this
-- model and recursively all contained models.

local function reflectAll( srcModel, mirror, tgtModel )

    for k,v in pairs(srcModel:GetChildren()) do

        if v.className == "Model" then
            local m2 = Instance.new("Model", tgtModel)
            m2.Name = v.Name

            reflectAll(v, mirror, m2)

        elseif v:IsA("BasePart")  then

            reflectOne(v, mirror, tgtModel)

        else
            local np = v:Clone()
            np.Parent = tgtModel
        end
    end
end


------------------------------------------------------------
function _G.reflect()

    local list = game.Selection:Get()
    if (not list) or (#list ~= 2) then
        error "Select both the model to be reflected and the mirror part"
    end

    local model = list[1]
    local mirror = list[2]

    if model.className ~= "Model" then
        model,mirror = mirror,model
    end

    if (model.className ~= "Model") or (not mirror:IsA("BasePart")) then
        error "Select both the model to be reflected and the mirror part"
    end

    local mmodel = Instance.new("Model", model.Parent)
    mmodel.Name = model.Name.."-M"

    reflectAll(model, mirror, mmodel)
end


-------------------------------------------------------------------

print("Select the model and mirror part and in command bar type: _G.reflect()")