if i was making a box for a car or truck i would have done that along with sand fill sand fill 20xs until its perfect lol but its for my p5 lol tomorrow ill sand prime paint and throw it in
Looks good. FYI all speakers require a certain amount of air displacement inside a sealed box to sound right. mostly subs. A little trick you can do is to add some polyfill inside the box to make the speaker "think"it's in a bigger box.