not so much a tool (yet) but rather a method which may be of use to someone in the future.
So - rescued from the bin a cheap camera tripod which was a bit beat up, but generally functional. The three ball mounted foot pads were missing - this article outlines how I replaced them.
1 - the balls were measured at 18mm in diameter, a 14mm hole was drilled in the top of a PET soft drink bottle lid (diet coke if it makes any difference)
2 - a small slit was then cut between the edge of that hole, and the sealing taper seat on the inside (it's the raised sharp ring which is designed for an interference fit against the inside of the bottle neck). The cap was then sat on the work bench, and the ball was forced through the 14mm hole. The cap is now "captive" on the ball.
3 - the threaded necks of 3 PET soft drink bottles was cut away from the rest of the bottle
4 - some short pieces of broomstick were cut (broomstick wood is a tight fit inside the neck of a PET soft drink bottle). The pieces of wood were put in the lathe and had a hemispherical cup cut in them (freehand - no form tool)
5 - the PET necks were screwed to the captive lids, and the wooden plug pushed in to determine the correct depth
6 - once the depth was set (enough friction that the assembly didn't "flop around") a 2.5mm hole was cross drilled under the neck flange through the wood, and short length of wire was inserted as a cross pin.
7 - the pinned neck/wood assembly was unscrewed and taken to the lathe and faced off so it was flat across the bottom.
8 - the trimmed foot was then glued to a piece of plastic (old store cards) to create a flat smooth surface - once the glue was set, the plastic was trimmed in the lathe.
9 - since the store cards were quite shiny, a piece of self adhesive foam rubber was then stuck to the bottom, and trimmed to fit with scissors.
10 - the feet were then refitted to the tripod, and the range of motion tested - about 25 degrees either side of vertical
11 - whilst not necessary, a quick lick of spray paint, and the new feet blend right in
hopefully useful to others in the future.
Des in Oz