Plugin Scripting Error

i’ve been working on a plugin for 2 weeks and i have a problem
as you can see here i’m drawing a shape and when i finish it’s just a Model
the problem is i’m trying so hard to know how to make it filled inside
not empty that what i need i searched every where but nothing helps

	-- Perform the union operation
	union:MakeUnion()    

	-- Set up the filled shape
	local solidShape = Instance.new("UnionOperation")
	solidShape.Name = "FilledShape"
	solidShape.Parent = Workspace

	-- Perform union operation to fill the shape
	solidShape.CFrame = union.CFrame
	solidShape.Size = union.Size
	solidShape:MakeUnion()

the output says "MakeUnion is not a valid member of UnionOperation “Workspace.UnionPart” "

You are trying to call the function MakeUnion of a UnionOperation, which does not exist.


There are no such functions called “MakeUnion” anywhere in the Roblox Lua API.

Oh, my bad
You have any idea about how to make a union bigger than the shape and then the union take the style of the shape to fill it inside?