Mostly , inroads into some more cylinder head patternmaking for a four stroke engine.
Likely entirely uncommercial, but a potential source of vast entertainment for all concerned.
Dinosaurs R Us......
A couple of years ago I made some little insertion tools for heat-set inserts (that screw, via an M7×1 thread, onto the end of my gas soldering iron):
Yesterday, I designed a 3D-printed part that had an M5 insert in a slightly awkward place, where the length of the soldering iron wouldn't fit straight up from the hole for the insert. I'd pondered just heating one of the above setting tools and using a pair of pliers to hold the setting tool and push the insert into place, but I decided that it wouldn't take long to make a two-part dog-leg setting tool: