Thanks for the responses. It took a while to make it. Months, but I only worked here and there. I bet a solid 30 hours though by the time I am done. I fully understand now why shops charge so much for them.
I have some how-to files regarding how to make fiberglass enclosures. If you are interested them PM me with your email address and I will send them to you. They were online but I pdf'ed them before the host took them down.
To make it all you really need is fiberglass cloth, resin, and hardener. You will need some disposable paint brushes, disposable latex gloves, and a respirator too. DO NOT do it without a respirator. I forgot to wear it once and was woozy in about 5 minutes.
For a rear camera mount you might only need a quart of resin. For this box I needed most of a gallon.
I would try to explain the process but it is very lengthy, so like I said, just PM me.