A long overdue project, should have done this ages ago, especially for my wife's bike that doesn't have a waxed chain haha. I think Brompton owners are used to having a chainring guard so when we swap to other cranks/chainrings they are sorely missed.
I think what finally made it feasible was when I started using Carbon Fibre Nylon as a printing material which has very good layer adhesion making this clip in design possible.
There's already a ton of 3D printed chain guards out there but they seem to be made for very specific chainrings or kind of haphazardly attached via zip ties.
I made the design with adjustable parameters so I should be able to just change a few numbers based on measurements from (almost) any chainring to make one that fits. I might eventually sell this so I'm not releasing the file but if you have the skills to design something similar, go ahead and copy it!
I always found chain guards a bit dorky looking but this design actually looks alright to my eyes and I think I'll keep it on my own bike (15g weight penalty RIP) even though the waxed chain means I rarely dirty my pants/trouser legs
by edtse88