Back in WW2, Stuart Turner produced a device, using a Sirius steam engine and an attached boiler – the Firefly. I recall it was described in ME years ago. It was used by partisans (Listen carefully; I shall say zis only wince) in France to recharge the batteries in their radio sets so they could communicate with London; fuel was just bits of wood and suchlike.
Stuart Turner then redesigned it, using a single-cylinder piston valve engine and a finned cast-aluminium boiler. There's an article here about this later type:
https://www.royalsignals.org.uk/photos/steam.htm
Anyway – I am now in possession of one of the latter variants. It's been used quite a lot judging by the soot on the boiler, but I am intrigued by the fact that it's aluminium – and it's been full of water for the last thirty years at least!
Here it is in its box with all the connecting pipes clipped into the lid:
Intriguing-looking piece of kit; I haven't connected up any of the pipes.
The engine has a variable-stroke feed pump and an integral lubricator pump also. Exhaust is directed up the chimney to draw the fire.
It even comes with a spare gauge glass in the box.
Has anybody ever steamed one of these with its original cast aluminium boiler? Those pressure cookers we cheerfully use in the kitchen (only at 15psi) aren't a lot different; you don't hear of many of those exploding.
I would imagine anybody wanting to run this device in public would have to make a new copper or steel boiler to get insurance for it.