How to build a hidden compartment in your truck

I decided to build this compartment to try and at least keep my "valuables" out of sight. I have fitted a locking mechanism to the seat but I don't wish to go into that here. If you enter amazon through my link https://amzn.to/3lhFqKz I get payed a small percentage of whatever you spend there. It doesn't cost you any more and I don't know what you've bought. Many thanks to those that do use my link. Its greatly appreciated.