LIKE SHIFTING LANES?
First off all, these 3D printed engines will not work like an actual engine despite it looking like the real thing. They won't actually compress any air, squirt any fuel, or be capable of withstanding any sort of heat, as it's made of ABS plastic. They'll melt, shatter into pieces, and possibly hurt a lot of people, if you ever tried to build an engine out of plastic.
However, as a desktop working model, these 3D printed engines are quite a marvel to look at. Powered by an electric motor, you can see how all of the intricate scale parts work in unison. Eric Harrell has reverse engineered the WRX's EJ20, the Toyota 22RE, and the Chevy LS3 motor and made it available on his Thingiverse account. He has even created several drivetrain pieces for those engines! He can be seen in this video talking about his efforts at the 2017 Maker Faire.
It's time to make ALL THE THINGS!