There was a thread awhile back that mentioned a WW ll miniature portable steam engine that was used to charge rafio batteries in remote locations. The engine fit into the boiler and packed into the backpack of a paratroooper. It was a great idea since a steam engine only needs water and something to burn to produce power. This idea returned to me as I looked sadly at my dead cell phone on a recent family camping trip. Solar chargers were useless in the rain (of course, I am a rain magnet when we camp), the little lithium power tanks were long drained (7 phones and tablets to charge), our car cigarette lighter doesn't put out enough power for some reason to do anything with a USB adapter and the local coffee shop had two power plugs available that were attended by lineups of campers trying to get a bit of charge on their phones. A little steam powered charging station would be a great idea. Everyone guarded their dry wood jealously for campfires. No limit on water supply. Great opportunity to introduce people to model engineering. So, I need some input on boiler design and suggestions for the engine. If the engine was going to pack into the boiler we would need something like a home pressure cooker with a lid that removed. Maybe adapt a small pressure cooker? It could just be put at the side of a campfire instead of using a firebox on the boiler itself. Does anyone have any info on the original WW II design? The dynamo could be built right into the flywheel to save space The idea of charging the newest fancy electronic gadgets with 300 year old technology is just too cool to resist.