The ClosetMaid shelving that was installed in our house uses a third wire that the clothes hangers can slide on. That bottom wire relies on the end caps to support the weight and stop clothes from sliding off the end.
We reconfigured our closets and needed on more endcap, but I couldn't find them for sale anywhere.
Printed in generic PLA, but if it doesn't hold up, I'll try printing a new one in PETG.
The author hasn't provided the model origin yet.