Just a curiosity of mine involving brushless motors
 

I know there are three main typed of brushless motors, Slotted inrunner, slotless inrunner and outrunner designs.

Of course there is really no way they can do slotless outrunners, due to the design.

I know 2 poles can either be slotless or slotted, But has there been it is it possible for a slotless 4 pole?.

In all the time i been running brushless, this has been the one question i never asked, but always wanted to know