Overbalanced smot-wheel or whatever.

[pinobot]

It's a bit quiet so here's an idea.

Picture is a bit messy.
It might work because on the left side the ringmagnet is attracted to the ramp while on the right side de ringmagnet is repelled by the opposite ramp.
I will post some other designs.

[pinobot]

Here's another one.
Works with metal balls.

[m668004]

Good idea. I like it. 

But I see a problem. The attraction will probably hold the ball/magnet in position, so it cant break free to roll away? What do you think?

M.

[pinobot]

yes, maybe, i'll have to draw one that repells all the time.

[pinobot]

Yep.