Can be printed without support!  But you should probably use it on the side parts of the hinge.

These use a filament latch and hinge that feels slightly looser than the standard lids.  Nylon is said to be more durable, however, even old brittle PLA still seems to hold up fine in the short term and gives a stronger latch effect.  I suspect PETG is the best material for the hinge pin and latch.

Each size has 2 versions.  The regular version has a flat bottom, for boxes that depend on the flat flush lid to hold stuff down, like the SD card case.  The hollow version is mostly for empty generic bins and gives extra space.  Take a look at them in 3D view before you print and be sure they will fit!

For the 2x2 size there's a slightly different design with a flatter top.  It is  3 units plus 5mm(Because Gridfinity Go! boxes are always 5mm less than a multiple of the gridfinity height unit) and is able to stack with other gridfinity blocks.  

The front ⅓ of a block will hang off the front and back edges, and there's no front or back lip, but it should stack well with other 2x2 blocks.

Pictured model is not sanded, it is finished with 3 coats of Titebond wood glue to prime and hide layer lines, followed by acrylic paint.

For compatible boxes and templates to make your own: https://www.printables.com/@SeventhSeeker_774132/collections/655951