While thinking about how to make a 100% printed rubik's cube mechanism, i came up with this idea: using rubber bands instead of the springs that usually give the center pieces the ability to spin and mantain tension.

(Updated Side piece - 8/1/2022)

You need at least one rubber band, so it isn't a totally printable design, but it works better than some others I've tried.

Printing is somewhat straight-forward. Place the flat sides of the pieces on the plate in your slicer and use supports from the base only to make it possible to print the overhangs. 

You will need: 

1 Core, 6 Center and Rectangle pieces, 8 Corners and 12 Sides for a complete cube.

Then, after printing you will need to thread rubber bands (3 small ones or a single longer one) through the core and the Center pieces, usnig the rectangle piece to make sure it doesn't come undone, like in the images. I used a single rubber band to do this and a toothpick to help, and it was difficult, so if you can I recommend using 3 separate smaller rubber bands. Maybe thin tweezers or some kind of small hook would make for better tools to aid in this step.

Assembling the cube after that is easier, but still more difficult than a normal cube, so be careful to keep the pieces in place. Because there is no solid structure for the pieces to follow, I found building the first two rows of pieces tricky, since the bands kept pulling the center pieces out of alignment. However, finishing the cube is easier than beginning.

This cube spins easier than other printed cubes, since the pieces i've designed are inspired in a few different speedcubes that I own.

However, it presents another problem. If the print isn't perfect (and the overhangs necessary for the correct shapes almost guarantee that it won't be) the chances that some pieces will snag while sliding against each other is much higher than with non printed cubes. 

As long as you are careful, you can use it at a normal speed, but trying to improve your speed on it can result in it collapsing and the pieces falling off. It should be fine as long as only one or two pieces fall, but because it uses rubber bands, the more pieces fall the more likely is the entire cube to fall apart on you. 

In the end, it can't stand up to an actual speedcube, so I will keep thinking about how to improve it, though even making it this far has been a challenge.

Also, these pieces do not exactly match any rubik's cube as far as I am aware, so they probably won't work as replacements, even if they are the same size.