I bought my first Unimat in 1965 (I was in high school) to support my model railroad hobby. I did modify a couple of locos so they would run at correct scale speeds. Added pulley reductions and flywheels, that sort of thing. This was before the electronic controllers were available.
I also started doing photography at the same time, also to support model railroad hobby. Take photos of the real prototypes to model, etc.
In one of those life ironies, I gave up model railroading when I entered college, but Unimats and photography have been lifelong hobbies.
I made a Sterling hot air engine as a science project when in the 11th grade.
Over the years I have used my Unimat(s) to make repair parts for various things about the house and vehicles. Also made a few things to sell on eBay. And making more Unimat accessories!
"When" I eventually retire, I hope to make engine models, maybe model boats. Mostly I just like tinkering with the Unimats themselves.