Bed clips for the Ultrabase. The Ultrabase has a tiny bevel (6mmØ) around the outside of the bed. This provides just enough of a lip for the clips to securely clamp the Ultrabase to the 3mm aluminium heatbed. Adhesive isn't required. I just left the paper attached to the adhesive under the Ultrabase. They sit flush with the top of the Ultrabase.

I printed mine out of ePC. Make sure you print them from a high temp plastic.
No supports required.