Mainly model-engineering and related (I'm presently making a Worden tool-grinder – a Hemingway kit).
Of the ones-off and "specials" – years ago:
– New king-pin bushes for Bedford CA vans I owned then,
– A set of small brass bushes for one of the CAs, to take out the wear in the rod-and-clip throttle linkage that was so bad it lost a third of the motion between accelerator pedal and carburettor..
– An adaptor in snazzy black plastic plate to hold a new shower mixer-valve on the previous unit's existing holes in the tiled stud-wall,
– A stand off, in Nylon, to take the shower head further out from the wall, necessitated by the bath end being a few inches from the wall,
– Perhaps the most awkward, a special connector for a pub trade CO2 bottle, being principally a short brass rod drilled though, with a very non-standard metric thread on the outside and a pin silver-soldered through as a handle. That on a 2.5" BGSC EW Stringer lathe with determinedly inch lead-screw and 25 to 65 T X 5T change-wheels – and of course no die or chaser to finish the thread to profile. It was for a heat-exchanger central to a warm-air breathing kit used by a cave rescue organisation to ward off hypothermia in the rescuee. The heat source is the exothermic reaction between the CO2 and soda-lime.
– Assorted parts for the spoilt-raising, manual winch for a cave "digging" project on Mendip, in which I am involved when not having knees replaced. It's essentially a simple rope-reel running on plastic bearing bushes on a fixed scaffold-pole axle, and I made the two side-frames from scrap miniature-railway bar rail. ("Digging": the signs are there that a cave is down there somewhere, but its entrance is obstructed by a very deep mass of boulders we are carefully and patiently negotiating and stabilising our way through. Some 150 feet deep and still going down…)
– Oh and when I've a few minutes to spare, my steam-wagon far too long in the making!