I created this as part of a larger project but it struck me that it might be useful for others. It's designed for an M12 nut, but should be able to be scaled to fit any. It creates a captive nut and if you print with sufficient accuracy the cover is a press fit; needing no adhesive.
I am very much an enthusiastic amateur when it comes to designing. My designs tend to have two things in common
1) They serve a purpose. I like to design functional objects which have a real-world use. 3D printing for art is fine, but it's its real-world application which will take the technology forward
2) Wherever possible I design to be easy to print and try to eschew supports or complex printing; modifying the design where necessary and possible to achieve this.