More testing showed TPU death stars to be highly durable.  It was noted flat sides of a circle weren't grabbing string as well as corners.   A triangle or star hole might grab better by presenting more corners.  The round holes were changed to triangles & all the clothing got death stars.  It was quite time consuming to have removable cord locks on clothing & remember which size to use for each item.

TPU welding has seen improvement.  The latest idea has been poking the soldering tip 1mm into the material & dragging it to create a moving pool of deeper melted material. 

Then a removable cord lock for #18 string was made.  #18 string has been the only use case for the removable variant.