I made one out of 3/8ths I think brass pipe by jamming something of a suitable shape in one end of the round pipe - and beating the living daylights out of it with a hammer...
I shouldnt admit I was channelling and imagining the pipe was my consultants head.. but what the **** - it looked quite good until someone nicked the bike
What you could do... is get the metal from a large beer can or something similar - scribe and cut two panels out and form something that way - soldering the edges would work because the exhaust is pretty much cold by that point - it would be worth putting in a support just to make sure the thing keeps its shape... and you'd be recycling
I am getting very tempted to sell my current bike and take a risk on one of the frame mounts and that appealing jackshaft/pipe/7 speed hub combo
, but all in all it cost me over £1000 and I am not quite ready to part with it for a massive loss...
Jemma xx