You can coat this structure with a two component aliphatic
polyurethane very similar to auto paint.
You will need to contact your paint supplier and ask for IR reflective pigment only to be added to the paint. You will only have about 12 choices of color, most in earth tones or black.
These...
I agree with the earlier response to coat your foam. A relative uniform coating thickness can be deposited with
a simple two component epoxy or polyurethane.
After the coating cures on your plug, apply a coating of mold release that can be buffed. There is no way that the parts will stick after...
