I'm having a bit of a problem with making a cover myself. I've made one out of a tin cookie box, using some aluminum foil as a "gasket", to achieve a better contact. It fits pretty snugly, BUT in the total darkness I can see quite a bit of light leaking *down* from under the lid: this light ends up shining on the paper for enlargements bigger than 5x7 (for 5x7 the reflected light is just next to the paper easel, but doesn't reach the paper).
I wonder if I can use some kind of heat resistant rubber as a gasket between the cover and the heat sink?.. Any ideas what kind of rubber I can use for this?