There are ten thousand printable hooks and not one of them says what it holds, or fits the door you actually own. Say what is going on it and where it is going, and this builds the part and does the arithmetic.
It arrives lying on its side, and that is the whole trick. Every layer is a complete hook, so the weight runs along the layers rather than trying to peel them apart.
Print it the way it looks natural instead, flat on its back with the arm sticking up, and every layer line lands on exactly the plane the hook wants to break along. It will also need supports under the arm. The same part, turned the wrong way, is a fraction as strong.
So: no supports, and leave the orientation alone.
| Material | PETG, or PLA |
| Layer height | 0.2 mm |
| Walls | 4 or more |
| Infill | 30% and up, gyroid |
| Supports | None |
| Orientation | As downloaded |
A hook is a cantilever. Hang a weight in the crook and the moment at the root is that weight times how far out it sits, and the section fights back with the width times the thickness squared, over six.
Which means reach is expensive and thickness is cheap. Reaching twice as far halves what it holds. A millimetre more thickness buys far more than a millimetre more width, and widening it is the least useful thing you can do.
Two places see that same moment, the arm where it leaves the plate and the plate itself, so the thinner of the two decides and the card says which. Thickening the other one changes nothing at all.
The rating is about a third of what the part would really fail at. That margin covers a cold garage, a thin wall, a print that under-extruded where you cannot see, and the fact that nobody hangs what they said they would. The fillet at the root is ignored on purpose, so the real part is stronger than the number.
Screws are the honest answer. The weight tries to rotate the hook off the wall, pressing the bottom of the plate in and pulling the top screw out, so the screws go high and the card tells you how hard the top one is pulled. Into a stud, or into an anchor rated for at least that.
Adhesive fails differently. A foam strip is strong in shear and weak in peel, and an arm that reaches further than the pad is tall turns the load into peel. Keep the back tall and the reach short, and clean the wall with alcohol, not a damp cloth.
Over a thickness is the one you cannot download, because your door is not anybody else's door. Measure it with calipers if you have them, a ruler if you do not, and print the Tolerance Kit once so the slot is opened by what your printer actually loses rather than by a guess.
The geometry is a small Javascript module. It runs in node as happily as here if you would rather script it.