If you want to run hydraulic disc brakes on an older bike frame or one that was designed for cable style brakes, these little adapters will allow you to mount your brake lines to the frame using the existing mounts and M3 hardware. I used 1x M3 bolt, washer and nut to mount each clip and then the brake lines clip securely to the other side of the adapters.
Something similar to this design can be bought online made out of metal but I couldn't find any .stl for them and I figured I'd save some money by printing my own. They seem to work nicely so far.
The author hasn't provided the model origin yet.