Help me with some case modifications

[Trevorus]

I have a hardshell case which doesn't fit any of my basses particularly well, and I want to know how to change that. What kind of material should I use to fill in the excess space and make it fit the form of the bass? I also want to re-cover the inside after adding the structural material as well. I could use recommendations for that as well.

[Rhythmalism]

You can start with a foam block and carve it out. There are also construction foams that expand, it could be possible to plastic wrap your bass, suspend it over the box, and fill the box slowly. The second option could have many things go wrong though.

Your local fabric store probably has some velvet or mabe another material that stretches pretty decent, which can be spray glued to the foam.

[Trevorus]

Yeah, but what kind of foam stuff are you talking about? Are you talking about that blue stuff they use to insulate under sididng, or just regular styrofoam.