I love my Rotring mechanical pencils, I use them every day at work and home. I printed this case to hold my set (a.7mm, a .5mm and a .7mm with blue lead).
Any 1/4" x 1/4" round magnets will work to keep it closed, just pay attention to the orientation you put them in. 6mm magnets will also fit.
Here are the magnets used to keep the lid closed: http://amzn.to/2tWIc18
Here's a link to the best mechanical pencil ever made: http://amzn.to/2tVe2v8
Here's the filament I used: http://amzn.to/2F5CYk2
Check out my Instagram at: https://www.instagram.com/designtheeverything/
These files are designed to be printed with any nozzle size or layer height. All files can be printed without supports.
I've included the original CAD documents, feel free to modify or remix them.