There is an account of a CS officer visiting one of the contractors who made bone buttons for the RD. I can't remember the exact number of buttons which the contractor could produce in a day but it was substantial. There are also some japanned metal trouser buttons which show up occasionally. I assume these may have been imported but that is only a guess on my part. The lack of metal trouser buttons dug in CS sites (union camps usually have many rusted tin trouser buttons) would also indicate that CS trouser buttons were made of a bio-degradable substance or some other material which cannot be picked up by a metal detector.