All the parts you need to make nipple clamps. The egdes are roundes to stop cuts and the plates are smooth but don't be fooled, these can really clamp down. It is two flat bars with thumb screws. No hooks for weights but you can loop over them.
The threaded screws and plate will work using noramal setting on a stock Ender 3 Pro. Put the heads of the screws down and lay the plates flat. I also used raft sysle platform.