Just another toy to keep your hands busy.

This one is customizable, so you're able to scale this thing up and down, tune the gaps for your printing skills and equipment, whatever ...

I included three examples as stl (their configurations are included within the scad source file):

• 20 mm (regular) - it takes 5 to 6 hours to print on my A6.
• 15 mm (small) - should fit better into a child's hand. I haven't tried to print this size, yet.
• 8 mm (ultra small) - 35 - 45 min. I just wanted to know what's possible. This is definitely not a beginner's choice. See https://www.thingiverse.com/make:474097 for some hints.

The decoration line can be used as a measure when to change the color, if you like to obtain a dual-color cube.

The red/black one and the tiny one in white is PLA, the green/transparent one is PETG (older model).

I included some helper models, that can be generated:

• cube - the entire fidget cubes readily assembled - this is probably what you came for :)
• hinge_test_vertical, hinge_test_bottom, hinge_test_top - two cubes and a connecting hinge. This allows to test the hinges in their various orientations without having to print the entire cube. The vertical one is the hardest - test this first.
• hinge, hinge_hole - a single hinge and its hole for whatever purpose.
• gap_inspection, gap_inspection2 - a cross-sectional view of two cubes and two hinges. It's only purpose is to check whether your customization will break something inside the cube. Version 2 gives a negative view of the surrounding gap with a corner opened to see all cross-sections.
• hinge_profile, hinge_hole_profile, hinge_gap_profile - these 2D profiles determine the shape of the hinge and its hole. The gap profile can be used to determine if the gap between the hinge and the cube will be well-formed.
• cube_profile - this 2D profile exhaustively determines the optics of a single cube's surface and edges

You definitely should also have a look at https://www.thingiverse.com/thing:2595224 and https://www.thingiverse.com/thing:2848678 . @austinvojta invested a lot of time in making his cube as printable as possible. He also provides lots of printing tips and solutions to typical pitfalls.