A shorter insert so it can go around the bend to allow it to be mounted more stable.
Seam hider is justa clip to put over a seam. I put mine from the underside so it acts as a retainer for the last part of te curtain as well.
I always loved making, braking, fixing, mending and abusing things. Especially the latter: making what I need by using things that were not intended for that purpose. A 3D printer is one of the nicest tools I ever owned: you figure out what you need, you find something that sort of works and then make the parts to bridge the gap. Custom parts for whatever purpose at barely any cost at all; maker heaven.