I am a licenced millwright and machinist and am contemplating making a tripod collar fo my 70-200f4, because I don't feel like spending 200 canadian for a new one from canon. It will hinge open and lock closed with a knurled knob, also permitting rotation, and a base with corresponding tapped hole/s. If anyone is curious in the least, if it works, I will probably make a few with the material i will scoff from work. Let me know
jgimp69@hotmail.com