Designed some anchors to secure the base of my Prusa I3 MK2S to a concrete paver. I drilled 1/4" holes, filled with epoxy and set inverted 50mm 6-32 (3.3mm) bolts into the epoxy. Hook_V1 worked to hold down the lower x-frame threaded rod but it could use some iteration for ease of use, flexibility and versatility.
Hook_V5 is designed so any curved surface, rod or threaded rod will be nicely secured up to about 12 mm in diameter at point of retention. The 4 mm diameter hole for screw or bolt is offset for ease of nut application and torquing.
I left V1 in case someone needs really close tolerances.