Any suggestions how to DIY (or improve on) this set-up?
DSLR Solutions - DSLR Follow Focus and Rack Focus Made Simple

Key Advantages:
1. No rails needed
2. No marker pen/eraser needed
3. No need to look at markings once they are set

Room for improvements:
1. Can be cheaper still
2. Velcro may not have enough grip on lens barrel
3. Must be removed for lense storage/re-attached on different lenses