I had Keith Mepham from XBandM make one for my 280cc MFR Buddy bottle. Cost £30 plus £2 p&p.

I had Keith make one that is slightly different than the normal type which requires an allen key to tighten / remove. My request was for one with an extended screw + lug so it can be fitted and removed without an allen key.

I will try and put up some pictures.