Where can I find plans to make a custom airbrush?

I already have a fixed double action airbrush (Simair Colani), but I want to make a custom little one specifically for detail/fine lines since I sculpt small figures and paint them myself. Now some may say "Just practice, and you'll get it", but seriously, I can only handle a paintbrush and use my Colani for base colouring (I'm really that bad and impatient).

I've searched a lot on the Internet and found nothing. All I'm after is something that will tell me what materials and tools I need to construct one (with pictures preferrably!) and I'll modify it from there. I'd like to make another fixed double action one since I am used to using one. Can anyone please help?