Rebuilding a combo bass housing (not a detached cab)

I have a biggish Fender Rumble combo amp. It's a pretty cheap amp, but I really love how it sounds and use it as my main gigging amp.




I let a friend borrow it for a while, and they put it in a leaky basement. It still works and sounds fine, but there is mold all over it. At the very least, I want to take it apart, rip the fuzzy material off the wood, and then clean it and put it back together. But then I got to thinking, maybe I should build a custom housing for it?

I would enjoy a project like that, and I think it would be cool to have a totally unique amp. That being said, I have found plans for building a stand-alone bass cab, but nothing about a housing for a combo amp. Does anyone have experience with a project like this? Are there any things I may be overlooking? Can I go wild with the design (within reason) or do the dimensions affect the sound? Also, can anyone recommend a supply shop to get amp specific materials?