I'm particularly fond of this one. I actually set out to make this; modeled after my Ferret. I started with the Gecko design and went from there.

Difficulty : Intermediate
Number of Bills : 1
Denomination Recommended : Any
Credits : Me

Diagram [PDF] (currently none)

Side
Weasel 01-01
Top
Weasel 01-02
Front
Weasel 01-03
Back
Weasel 01-04