A friend of mine had a drawer with his insulin pens and needles just rolling around. I printed a case for him, but it didn't fit his need cap size, and didn't seem very secure, so I tinkered around and created this series of cases for him. 

These boxes will hold both the short and longer needle caps.

They are not print in place and will require assembly, but  you won't have to purchase any special bolts.

I have created pins that print with the boxes and latches that slide into place and hold everything together.

Make sure the flat side of he pins are facing the bottom and insert from the outside of the box by pressing the square side of the pin. Like this:

The pins are tight enough that you shouldn't need glue, but you could add a drop of super glue if you want. 

You will need to “snap” the square head of the pins into place by pressing them with something hard. 

I use the side of a pair of pliers.

UPDATE 2025.05.21

I reduced the diameter of the pins by .1mm to be slightly easier to install, and revised the “hook” of the latches to be easier to open.

Revised latch:

UPDATE 2025.06.18

As requested by @Rooj I posted the cases without the injection logo

UPDATE 2025.02.03

I added a profile for a case that holds two up to 180mm length pens, 7 needle caps, and had an area for alcohol wipe pads. It is also 3mm shorter than previous cases.