In a message dated 2/12/00 11:47:09 AM Central Standard Time, tesla-at-pupman-dot-com writes: << The plastic could be routed on a mill so there is a slot down the length of each just as wide as the copper pieces. >> Do you mean a slot as wide as the cylinders are long? Sounds interesting if all the cylinders are the same length. Bought couplings are of uniform length. cheers, Ralph Zekelman