A hole in the wall X4 - a liftout bridge (page 12)

[nachoman]

I wanted to try using Homasote on this layout instead of foam but it seems Homasote is not available in Arizona or California unless I want to order 96 sheets of it. Anybody ever use soundboard instead?

Nope, but thought about it the other day. It doesn't look like it would hold up too well for cutting into smaller pieces. It doesn't seem to be bound tight enough, but may work okay if you are using a whole sheet and have it well-supported. I bet it will swell up with the glue/water when doing scenery.