You could have a wheel with alternating positive and negative-faced magnets that pull it along.

IDK :/

A slingshot of some sort?

Angled rear facing magnets with removable cover?

 

BtB

That sounds like it would work, but it would require magnets with alternating polarities.

Argetlam

Tape a ninja to it.

This. XD

Add wheels that stick out, so that it can roll on the walls. Only two is fine. Also, where did you get the magnets?

I was thinking some sort of cable-car type thingy. Bungie-cord/string running above the track, motorised wheel sitting on the cord/string, bish bash bosh.

(BTW I actually had this idea ages ago but the server hit me with a rake when I tried to post it)

Wait, what propeller are you thinking about? I heard Black Propeller 2 Blade 9 Diameter propellers are good.

That looks amazing.

Since the small motor rotates so fast I think attaching a propeller to it would probably give you a little bit of movement. Since there isn't any friction, or less than there would be otherwise, using a gear chain to increase the speed of the propeller would probably be effective.