Doreen Greenstein's book, Easy Things to Make Things Easy, describes/shows a One-Handed Garden Tool Handle, constructed using a 2-liter plastic soda bottle and a hose clamp. To make the hand grip, cut 5 inches off the handle end, screw the hose clamp to the cut end of the 5-inch piece, then tighten the clamp onto the handle at the appropriate location for a handhold. To make the handle's arm saddle, cut a band of plastic from the soda bottle, and screw it onto the top of the remaining tool handle. Another way to accomplish the same thing is to fasten the end of a forearm crutch onto the end of a shortened tool handle.