[ivconic]

http://www.youtube.com/watch?v=jYcjjSfiNNE

This i like most. Why? Simply it is cheap to make it and do experiments.
Before moving to something more expensive, this would be first step.
I have problems to get neodymium magnets. Especially rollers like on this video.
Searching through my scrap piles i founded excellent neodymium magnets in old, broken hard disks. Every hard disk do have 1 or 2 magnets inside.
Those are glued hardly on heads anchor arms, covering both sides of coil. Problem is those are awkward shapes. Hard to adapt to what we need at magnetic motor. Sheeesh! And firstly i was delited discovering those!