I designed this 1/25th scale Go Kart engine in SolidWorks and had it printed by Fractional.
The crankcase with pull starter was grown as one piece. The cylinder/head and carb were grown as another.
The chain, sprockets and clutch are one piece and the exhaust is one more piece.
I machined the tank, cap and velocity stack from alumminum.
These are the wheels (two piece) and tires for it done with the same process.
See more in an upcoming issue of Scale Auto Magazine.