3D printed parts. input on design ideas?

Hello all, I am new to the community here. I recently bought a .40 BG and quickly realized I didn't like the parts on it. While I started the process of designing some new parts, like the coupler for the two barrels and anew mouth piece, I came across some threads on copper pipe builds. I already had a piece of 1/2 copper so I played with that for a few hours and then went to the hardware store and bought a 5ft stick of 3/4. This evening I printed out my first mouthpiece for the 3/4 pipe. I will upload a picture here in a minute. What I am curious about is when you guys build your own mouthpiece, what shapes and designs do you prefer for a better fit and feel? I'm going to make an anti inhail lip in it on the next revision that will work with the dart cones that I am also making (not 3D printed). I would like to put a few bgs together for my buddies and their kids and need some input on style. Thanks for any advice guys.