Very amazing! I think this is like climbing a mountain. Sure it accomplishes nothing long last lasting but it's still impressive to me and a shows off skills.
I build paper* rockets now and then and building them isn't easy. I look forward to a seeing a paper* steam engine built. I think it is very appropriate for this forum.
*Obviously there may be glue, expoxy, plastic, rubber, etc involved too!
Someone in the home of that video is a fairly avid paper cardstock modeler!
In the video, on the steam engine, you see him pull the steam tube off and replace, it is a ring magnet! This is your "safety valve" in "tips to improve" performance, you can place a couple drops of Heavy oil on lid and fit magnet, the heavy oil slightly improves steam seal. "Small" gains matter as these run on very Little steam pressure.
I have seen a video of the Paper Stirling so well constructed, the Flywheel ran as true as a CD from a CD player!...Have seen one of the Paper steam engines that was built almost that well.
I enjoyed your Mountain Climbing Analogy....thanks for sharing CBWho!