How do i fix this

How do i fix this it keeps coming out as “GetMass is not a member of part”

local Part1 ="Part",workspace)
function Part1:GetMass()
	local volume = self.Size.x * self.Size.y * self.Size.z
	local density =
	return volume * density

You can’t create a function on a physical part. You would do that on a table. (That is what you’re trying to do in the script)

Consider converting it into a local function instead called GetMass.

If you’re trying to learn about OOP, check this, probably will help you