A little book-style box with a living hinge in various sizes.

The smallest one fits for SD-Cards, one is fine for credit cards, one for playing cards. The biggest one doesn't fit on my Prusa Mini.

Heavily inspired by Eng. Yehia's Living hinge box, but made completely from scratch, with a more sturdy hinge and a clasp that doesn't need a magnet.

I used PLA, 0.2mm layer height with a 0.4mm nozzle. Insert a color change in the slicer right above the cover layers for a more bookish design.

I prefer the textured print bed over the smooth one, but PLA doesn't stick to Prusa's textured sheet well. I'll probably buy a satin sheet.

Declaring this as mechanical marvel is a bit overstated, but living hinges are often used for rounded edges in laser-cut wood designs, and I think it has it's place in 3D-printing, too.

Edit: Added more sizes: one for 3*AA and one for 3*AAA batteries. I call them the Books of Power :) Note that the 3*AAA box fits nicely into the 3*AA box :)

Edit: Added a version for 2 decks of cards and one without the inner spine per request. If you need a specific size, make a comment and chances are I'll upload it.