Pipe keys,
The key suppliers here in the uk sell them and should have them at a suitable size for your job,
Try
www.skskeys.co.uk they will almost definatley sell somthing that will fit,
If you want to make youre own and a normal (non holed) key is easy to make then simply make one of those and get someone to drill a hole through the middle ona lathe,
I can not comment from experiance on what ive suggested about driling holes as ive not done it and instead get the proper blanks but its an idea,
The other alternitive is to get some tubeing and weld/braze/solder etc etc a bit on to the side of it and form a bow,
If this is a job and its for a customer you need a commercial key and as i say sks will be my suggestion for them, maybe now you know they are pipe keys you may find them neaer to you on the net,
