A tube box with a cap. You can screw the cap on the box. Quite simple concept.

In openscad, you can choose the size of the box.

There are also some options:

- adding grip on the cap;
- adding holes on the bottom of the box and/or on the cap.

You need to have threads-library-by-cuiso-v1.scad in the same directory. It can be downloaded at https://www.thingiverse.com/thing:3131126

I print my boxes with 0.2 layer height. The threads are ok.

No support needed.