This is a two-piece ceiling hook assembly. Mount the anchor with a screw through the center hole, and then push on the hook, and twist 90 degrees to lock it into place. A small line on the anchor shows which way the hook will point.
This hook was designed for use with a drywall/plaster anchor, although you could also screw it directly to a joist. Or anything else, really. The hole and cavities are sized for a No.8-12 screw, but should fit larger screws as well.
Toleranced for a Replicator 2. See print instructions for details. The hook_stronger variant is thicker. Designed in Autodesk Fusion 360, with some manipulation in Autodesk meshmixer.
I print the hook on its side, so that the outer shell layers run around the hook. This results in a much stronger part than printing vertically, because of the thin sections. For the anchor I print with the small rim on the bed. This avoids warping on the mating surfaces.
I print these at .2mm / 3 shells / 25% infill, for strength. Total print time for both parts is about an hour.
I use makerware support for both pieces, and a raft for the hook. Make sure to be thorough getting the support out of the inside of the hook base (I use a small wood chisel, works great). Since it is a ceiling hook, it is far enough away that you cannot see the details, so I don't bother with any sanding/etc.
The tolerance is tuned for a Makerbot Replicator 2. Initially the parts will not fit (do not try to force them, or the anchor will get stuck!). Screw the anchor down to a piece of scrap wood, and push the hook up and down a few times until it slides smoothly. Then do the same until you can just barely twist it into place (careful not to snap the hook).
The rim on the base is there to leave space for a drywall/plaster anchor, and so should end up flush with the ceiling. Screw it on, twist on the hook, and you are ready to hang something.
For the stronger variant, I have included a small sizing print, if you want to check that the hook will be big enough for your purpose. It is just a slice of the hook, prints in a few minutes.
No idea how much weight it can support, but the "stronger" variant is currently holding up 14 globe bulbs hanging over my dining room table.