Why not just fiberglass it? Instead of trying all these funky wood working skills? Fill it with shipping peanuts till you get your cubic feet & boom boom your done! Well it's a little bit more work but yeah...
2015 Mondo
Upgraded 900lb Rears, 250lb under Port Seat & 750lb IBS
2079 Prop
Auto Flow 2.0
Kicker Stereo: 2 800.5 amps, 2 400.2 amps, 4 KM8 towers , 4 KM10 subs & 8 KM6 cabin speakers