its just 1" R 5 foam board. I used the rest to insulate my basement about 18 years ago. had the lid to a fish tank lizard tank thing for a lens and I light fixture screwed to the side with a chunk of cement board as an insulator and for mounting. if you look there is handles screwed on the ends that double as mounting points for the light. I found I has a chunk of fiberglass eve light that was corrugated and fit the bottom well. the eggs stay spaced and the ripples make it easy to flip them and get them to stay where you put them.
if you looked inside there is a brace above the window made of 1/2 osb. its so the edge of the box didn't give way when the window was cut. secondly there a pool thermometer laying on the eggs in the bottom as back up. it also has a dish and sponge under the light for humidity.
the box is glued using auto rtv silicone. any kind would work but I had this handy. I used 16 penny nails as spikes to pin the box and let the glue dry.
