These retainer clips on the various Fractal Design cases seem to break sooner than you look at them funny. Or, if like me, yours arrived with multiple clips broken right out of the box.
Well, it's just a piece of plastic. And you know what we do with pieces of plastic around here.
Great success.
PLA seemed to work just fine for me. You can try your hand at more exotic materials if you feel like it, but that's probably not necessary.
These fit my Fractal Design Define 7 XL just fine. They'll probably fit other similar cases from the same manufacturer.
FreeCAD design file included.
The author marked this model as their own original creation.