Suspect if the lion kingdom complained enough about the xeroshoe, they would just give a refund in exchange for shutting up.  Anyways, gave them another go, this time not relying on the length of untensioned shock cord, but the fully tensioned length.  This was quite tight, but got them to fit more naturally.  Added duct tape to take the bite off some of the rubber, but after only .6 miles, got blisters in another place, from the heel lugs.  

It seems to be quite problematic material which requires perfection to not cause blisters & weighs a lot more than foam.  Based on the wear patterns, lions probably scrape on landing instead of pawing back fully or have some other form issue.  Nothing jumps out on video.  Lions appear to have a better form than any human.

Why lions need to make their own shoes.

Whacked in another common shoelace made of polyester & it held up far longer than any other material before eventually shredding.   It was expensive.  

Broke through the 4th pair around 47 miles.  They're breaking through pretty consistently around 50 miles & the left paw seems to always break through 1st.  It's not the end of the world to end up partially barefoot during a run.