I used spray glue to hang my mylar. It was very handy and works great. It has been hanging on both drywall and particle board for about 3 years now with no problem. Of couse plywood is a better choice if you plan on spilling water on it, but plywood is more expensive than particle board. If you really want to go all out use marine grade plywood, but why bother with that on walls? Maybe on something more likely to get wet.