I have a script that makes parts in workspace smooth plastic but how do I make it so it turns off?

This is a local script. The top half of the if statement works. The bottom half I need help with. The original material is the material of all the parts in workspace but the materials arent the same.

local Smooth = Enum.Material.SmoothPlastic
local UnSmooth = Enum.Material -- Original Material?

script.Parent.MouseButton1Click:Connect(function()
        if script.Parent.Text == "Off" then
        script.Parent.Text = "On"
        for i,v in pairs(workspace:GetDescendants()) do
            if v:IsA("Part")then
            v.Material = Smooth
        end
	end
    elseif script.Parent.Text == "On" then
           script.Parent.Text = "Off"
            for i,v in pairs(workspace:GetDescendants()) do
                if v:IsA("Part") then
                         v.Material = UnSmooth
                        end
                    end
                end
            end)

Maybe try saving the original material of each part before it is turned smooth like this.

local Smooth = Enum.Material.SmoothPlastic
local UnSmooth = {}

script.Parent.MouseButton1Click:Connect(function()
	if script.Parent.Text == "Off" then
		script.Parent.Text = "On"
		for i,v in pairs(workspace:GetDescendants()) do
			if v:IsA("Part")then
				table.Insert(UnSmooth, v.Name.." "..i " = " v.Material)
				v.Material = Smooth
			end
		end
	end
	elseif script.Parent.Text == "On" then
		script.Parent.Text = "Off"
		for i,v in pairs(workspace:GetDescendants()) do
			if v:IsA("BasePart") then --//This is better off BasePart
				for _,t in pairs(UnSmooth) do
					if string.match(t, v.Name) and string.match(t, tostring(i)) then
						v.Material = t
					end
				end
			end
		end
	end
end)

I think it won't work ;-;

Hopefully this worked for you and if it did please accept answer.

Thank you.