This foldable Mobile Stand ist easy to print and to assemble and comes in handy in lots of situations.
All you need is a little sanding paper or a small file to grind off the extra material at the bottom edges. You can print upright without supports (no angles > 45°) but for a good adhesion you should add a brim of four or five millimeters. If you prefer to print flat no brim is needed but do add supports (~10%). To remove the supports you shoud have neddle-nosed and side-cutting pliers at hand, also you will need a small round file. It will be a little tricky to remove the support from the hinge's hole and you want to thoroughly remove any extra material from inside the hole to make it work smoothly. This is why I prefer to print it in upright position without any supports. I usually print both parts in one print-session - but I leave this up to you.
After you have prepared the two parts simply slide the upper part of the hinge (of the right piece) into the lower and you're done!