This one has been quite a pain in the a$$ to print. I use Simplify3D and when I would slice the model, there were several voids in the surface for some reason. I tried Slic3r and that actually worked better. Printing in TPU is always a pain to try to print so I ended up printing a 50% infill and at 15mm/sec speed with supports. I think that it would have come out better at an even lower speed (around 10mm/sec).
Print at around 10mm/sec with NO RETRACTION