Ah, you're right, I was measuring in cm and calling it mm. All thanks to my high powered measuring device, a plastic grade school ruler. That's why I left the CAD changes to the experts.

Right, the knob is 1 cm from the lens. But didn't people request it to stick out more? I could make it 1.5cm or 2cm from the lens, making it easier to grip.

Ah, I just don't know about this one or two piece shaft thing. Now I'm inclined to use the one piece shaft, because will it really work loose over time? A tiny dab of hot melt glue could easily fix it.