Soundproof grow area

20 slot Egg cartons mate, great sound dampener, used it in a band practice room years ago to dampen sound and it worked a treat - same prinicipal as sound proof foaming but a whole lot cheaper. If you were to build a front you could put stick the egg cartons inside to dampen sound. Another cheap alternative is expanding foam between 2 thin pieces of wood - get some clamps (6 should do it) spray your foam LIGHTLY across one board, stick the other board on top of itnand clamp them down so youve got about an inch gap for the foam to expand and itll stick the boards together too, use sparingly cause it expands like a mo'fo, some of them are also fireproof too, if youre the safety conscious (paranoid) sort. ;)