Homemade wheels would be made in a forge, with low health
You’ll need more than a forge. You’ll have to have a pretty big lathe to turn your steel or aluminum castings to a true round shape.
I like the steam engine idea. I’d suggest that it involve making all the parts first, pistons, boiler, firebox/burner etc then assembling them into a unit. Multiple fuel types could be possible as well, wood pellets, alcohol etc. The type of burner you use can drive the fuel type the engine takes.
Now is it possible to make a single engine consume both fuel and water?