These were made for the Gopher Pick Up & Reaching Tool for a relative. One of the cups disappeared from the grabber so I made a replacement set for it. Since I made it from TPU it is flat across the surface. I have yet to try to use supports on TPU. Not sure how well it would work. Since I made them a long time ago. I am guessing on some things. I believe the hex in the cup for the nut is 3mm. 

Used generic TPU filament, fairly stiff. 20% infill, no retraction, Since it is like a hard rubber I might suggest gluing something on the pads for better grip. I looked on the Harbor Freight website and their grabber looks very similar.