When I was around 20, I started a small side business building custom speaker boxes for car audio for competitions. I mostly did work for friends and got paid in beer more often than money but it was fun and I learned a lot. I was obsessive about making good boxes so I read just about everything I could get my hands on to design the highest quality boxes. A box has to have a specific volume in order to sound right, think of a bass speaker as drum and the box tunes the drum. I don’t have any pictures of the boxes I built back then but a few of them won some ribbons.
About a year before I moved to CO I bought a 1994 Toyota Pick Up, regular cab, 4X4 with a 4 cylinder. Great little truck but it could only go about 25 mph up any hill and there was almost no room behind the seat for a speaker. I picked up two 8” Lancer subs somewhere and built a custom box that allowed me to still move the seat all the way back, I’m 6’3” and mostly legs so I didn’t want to lose any leg room. To make the box smaller I used the truck as the back of the box but lined it with dynomat to keep it from vibrating. I always intended to fiberglass the inside of the box but never got around to it. I made custom speaker grills on the CNC Turret Punch we had at the shop in LA.
For a later system I drew and cut this speaker grill but never finished the system. I was fixing up a 79 GMC Sierra short box but sold the truck to buy my trailer before I ever finished it.
I wish I had pictures of some the custom boxes I did back in the day but that was over 20 years ago now. I also built a custom box for the 98 Tacoma that went behind the driver seat and took up very little room. The Tacoma was an extra cab but I still wanted a small incognito box. This was a quick and simple build but it utalized the space well and didn’t take up too much room. Calculating the air space of the box was about the most complicated part of the process but it wasn’t too hard. When I sold the Taco I kept the sub and intend to build a box for the Chevy soon. I’ll update with pictures when I do.