Camera "Monopods" (Like tripods but with one leg) can very very rigid if mounted right
Actually I have made a bunch of this sets ups for "Inner corners" with cheap tripods, since each leg can be adjusted, you can control the light position and angle very well..
Bouncing of the walls or direct, on the inside or outside, just keep in mind that with Three legs you can place the light exactly where you want it, vertical/downwards if you are working in the engine bay for example..
Also call me cheap, personally I call it "pennytech"
bicycle stems make some great mounts, the "Quills" can go inside tube (like Yakima racks) or the treeless come in three usual diameters 1"/1 1/8"/1 1/4" and the "Face plate" in 22mm 25.4mm, 26mm (old school road bike) and 31.8mm (you can buy them for almost nothing and they come in all kind of lengths and angles
Windsurfing, oh man endless possibilities, light carbon mast that break all the time (big wave riding)
Motorcycle triple clamps (bicycles with dual triple clamps too), oh man all kind of diameters, super rigid plus many come with a bunch of bores already made.
Just think "Three world country"