This is a 3D printable keychain container. My girlfriend wished she could find a keychain pill bottle that could hold exactly three of her medication – so I designed and 3D printed one. 

I made the design fully parametric, so you can go into Fusion 360 and customize it to whatever size and tolerances suit you. To customize the parameters, download and open the .f3d file in Fusion 360, go to Modify > Change Parameters, and then adjust the following parameters:

1. Inner_Diameter: The interior of this pill bottle is a cylinder. This is the diameter of that cylinder. 
2. Inner_Height: This is the height of the interior cylinder. 
3. Thread_Tolerance: This is the wiggle room left between the screw cap threads. By default, it's set to 0.2mm, but my Bambu Labs P1P was able to handle 0.1mm – it just required a bit of working-in after printing, and now it screws/unscrews wonderfully. 

In case you don't have Fusion 360 (it's free for hobbyists, btw), I have included a few different preset .stl files in the Downloads section. 

I printed the bottom piece with the hex head flat on the table, and the top piece with the keyring loop facing upward – so both parts were printed in their vertical, upright orientation. My 3D printer was able to handle the bridging without issue, but I suppose you could use supports if needed.