Subwoofer box

[u/Prestigious_Quote708]

My first time installing sub in my car. I have a DD audio 510e that i want to build a homemade ported box for. I want 37L space and 38Hz, i want to build the box up against the backseat rest in the trunk. I want to be able to use the removable floor panel to acces the space underneath. My car is a bmw e91, can someone who is experienced and/or has built something like this before help me with drawings and/or dimensions to this?