great stuff/false back

So I read this article on using pond foam to from false backs in Aquarium Fish International...... seeing as I really don't want to do my computer nutrient analysis for my nutrition class, I think I might go out and get a can of this stuff and try making a back for my 8.5g nano. Anyone got any tips before I jump in and start making a big mess?

 

Lay your egg crate frame on wax paper on a flat surface so the foam doesn't bulge out the back.
Spray the foam slowly and evenly to cut down the amount of waste you'll get from trimming.
Cover the foam with epoxy resin and sand to make a more natural look.
Silicone all of the exposed edges to keep detritus from collecting behind the wall and becoming a nitrate mass production factory.