Nice setup, I knew you'd find some way of 3D printing something for it! The holder is very neat, by the way, if using jars it should be better than the hook-type thingy I have. Amongst my airbrushes is a Paasche like yours, very simple to use (and clean) and great for general use. It does require a higher pressure to run than internal mix units but for coverage work, as opposed to detail, it's a better brush to use. Rather than use an air splitter I fitted quick-release adaptors to all my brushes, simple to swap them and I only have one hose to avoid tripping over!
Good writeup.