OK then, let's get started.
This Instructable is a part of the 3D Project Challenge: Money Clip. Create your own 3d file for a money clip or modify the template to enter.
Step 1: Design issues
Tinkercad.com is great ant their tutorial for a money clip is great for learning, but the results weren't so hot once I printed them. Too big and bills easily fell out when I printed it on a MakerBot Replicator 2.
So that leads to two things to fix. The size (no problem) and the grip (a bigger problem).