(Note: I now have a latching and waterproof version of this box, with Fusion 360 source files: https://www.thingiverse.com/thing:3338826)
A tough little box to protect your delicate electronics or valuables when you are out and about. The lid snaps into place very firmly. I designed the clips to provide some static load, to keep the two halves firmly together. The interlocking seal helps to keep dust out, and offers some protection against water ingress.
To open it, carefully lift both clips on one side at the same time. Intentionally, it can't be opened by lifting one clip at a time.
How water resistant this is will depend very much on how you print it. I printed this with 3 perimeters and four top layers. I filled the bottom half with water and found no sign of leaking, even after a few hours. Nevertheless, if you want to leave it in the rain for an extended period I'd recommend sealing the outside by painting it. Also, the interlocking seal will only protect against rain properly when it is in the upright position.
This will print without supports, as shown in the attached image. The clips extend from the base at 65 degrees, which should be fine for most printers.
Printed at 1 to 1 scale, the internal dimensions are 120mm L x 70mm W x 62mm H, with a 15mm radius in the corners.
I can confirm this works well printed down to 60% scale.
I've also added a version 1a lid, with slightly thickened sections around the neck of the clips.
For anyone who wants to experiment, I've added a new model for the top with an o-ring groove and a printable o-ring. I don't recommend printing the o-ring version unless you want to experiment. If you want something truly waterproof, use my new box:
When printing you will have the obvious trade-off between weight and how rugged this box is. I had good results printing this with a 0.4mm nozzle, with 0.1mm and 0.2mm layer heights. Much larger layer heights might reduce the performance of the clips, I don't know.
When printed with 3 perimeters and 30% infill, this feels rock solid. You could probably get away with 2 perimeters and less infill for many purposes.
The box in the photo is printed with Verbatim White PLA for the bottom half, and Paramount British Racing Green PLA for the top.
The clips might work even better if it is printed in PETG or Nylon, if you try it, let me know.