i think he means like custom making a headtube for a scooter. i doubt you could buy one anywhere. i dont think you will be able to purchase cromoly at your local metal shop. im not too sure though. if you cant get any in your area, www.onlinemetals.com
Youd have to chop off a BMX headtube, then weld it to to your scooter or something, which would be retarded. I think your talking about a BMX headset. Read the supper modding thread.
Aight, thanks guys, I'll just find a crappy frame and cut the headtube off. And it's not for a scooter... or else I would have posted it somewhere else.