MDF is what your supposed to build your boxes out of lol, if you dont they will sound like ****, all he has to do is put some sealant on the outside of the box and it wont matter. Looks good so far man, what color did u paint it
I fiberglassed the complete box after i loaded it up with the amps and wireing! I also have computer fans pushing and pulling air from the cab for the amps! I built a trap door if I ever need to service the amps!