Most silent motor out there

I'm on a quest to make a small electric toy for my cats that will just run/crawl around the house. I've went thru tons of similar toys form Radioshack, etc. and they all have one big problem. Motors in them is freakishly noisy, even in tiny toys size of thumb. It scares cats. Is there a small low power motor that's almost totally silent? Can you recommend me one? :) Not sure if best would be stepper, geared or servo...

DC motors run at high RPM and almost always are geared down. Cheap toy gear boxes tend to be noisy. Stepper motors often do not need a gearbox.

Smaller motors are quieter, especially if the case has no ventilation holes. There are some nice micrometal gearmotors on eBay that are about 15mm across and various voltages and gear ratios.

For lower speeds/powers computer case and CPU fans have a brushless motor that's very quiet - you'd have to find an old one and cut off the fan blades and housing.

MarkT: Smaller motors are quieter, especially if the case has no ventilation holes. There are some nice micrometal gearmotors on eBay that are about 15mm across and various voltages and gear ratios.

For lower speeds/powers computer case and CPU fans have a brushless motor that's very quiet - you'd have to find an old one and cut off the fan blades and housing.

Thank you! That's a good idea about fan motors! I have some from old videocard :)