Quote Originally Posted by Mike41793 View Post
No melamine is fine bc people use it for racks. I misspoke in my last post, i apologize. If you build it out of melamine i would just seal all the seams with aquarium sealant and you should be all set. What do you plan to keep in it?
Melamine (the particle board substrate) is actually quite toxic. It has formaldehyde and urea glues used in MDF and particle boards. Most plywood is glued with similar phenolic resin glues that once catyalized have less out gassing also the glue joint is very small only the very slight edge where particle board the joint is the full exposed width.

The shop I used to work in particle board and MDF required a use of a respirator to work with it.

I would expect plywood to be far less toxic than particle boards especially looking at the MSDS sheets for various products. Any bare wood needs to be sealed in any case. I would not use cedar ply but the fir (douglas or spruce usually) is fine and pine is fine if it is kiln dried (all ply is) but if asked I would really use either plastic or birch ply it is 1000 times easier to work with (flatter and less voids fill spots ect...) and seriously stronger.

melamine is used usually because it is cheap.