Using a combination of rubber bands, old pieces of acrylic, some tubing and fishing line. You can DIY a 3D Printer.
The design looks a little unconventional but that’s because it’s not your standard X,Y,Z layout. This non-cartesian (that’s official name for the x/y/z part) is driven by the length of the three pairs of fishing line that run to the print head.
Shorten all three and the nozzle in the head moves up, alter them at different speeds and the head can be made to move left/right/forward/backward/up/down in whatever combination you feel like.
Take a look at this video to see more.