The knob design is published on Thingiverse: http://www.thingiverse.com/thing:1160160
Before the upgrade:
After the upgrade:
Obviously we need to redesign and reprint the panel markings to accommodate this much larger knob.
The knob was designed using OnShape.com, a new (still in beta) parametric 3D CAD system that's free to use with almost no restrictions. Worth checking out.