Polyethylene painters drop sheets. Use 2-3 mil if you can get it. Perfectly clear, large enough to cover even very large plans, and nothing sticks to it. Not CA, Not epoxy, even paints and dope will peel right off (once dried). I'm sure there are some adhesives that will form a bond, but nothing we use that I am aware of. What's better, it's available cheap @ any hardware store, Even XYZ-marts have it.