Just a thought but maybe you could pick up and rebuild a used motor, maybe even from a scrapyard, rather than building your own, if the price is right. The only issue is that the motor may have to be internally re-balanced depending on how much you have to rebuild it. At the very least you could dissect the scrapyard motor just to see how complex it really is and base a home brew design from it.
As far as building one yourself, there are hobby level diy motor projects around the web, mostly used for model aircrafts, but there have been some that have been used for things like scooters. However, all the ones I've seen are all brushless designs, and most use neodymium magnets, which will lose their magnetism at relatively low temperatures. Even then, they all have some sort of machine shop at their disposal.
small scale:
http://www.rcgroups.com/forums/showthread.php?t=665032
larger scale:
http://hackaday.com/2010/02/18/build-your-own-hub-motor/
I'm sure this is not what you're looking to do:
http://hackaday.com/2010/08/23/a-different-take-on-electric-motor-cars/
As to why few if any actually scratch build a brushed motor, I think (and I'm sure someone will correct me on this) that it has to do with the complexity of the whole brush design.
As far as building one yourself, there are hobby level diy motor projects around the web, mostly used for model aircrafts, but there have been some that have been used for things like scooters. However, all the ones I've seen are all brushless designs, and most use neodymium magnets, which will lose their magnetism at relatively low temperatures. Even then, they all have some sort of machine shop at their disposal.
small scale:
http://www.rcgroups.com/forums/showthread.php?t=665032
larger scale:
http://hackaday.com/2010/02/18/build-your-own-hub-motor/
I'm sure this is not what you're looking to do:
http://hackaday.com/2010/08/23/a-different-take-on-electric-motor-cars/
As to why few if any actually scratch build a brushed motor, I think (and I'm sure someone will correct me on this) that it has to do with the complexity of the whole brush design.