A shelf that needs holding up, a panel that will not stay square, a bought bracket that is the wrong angle or has its holes in the wrong place. Set the two legs, say what screws go through them, and this builds the part.
Both legs are measured from the outside corner, the one that sits against whatever you are bolting to. That is the number you get by holding a tape into the corner, and it is the number that decides where the bracket reaches.
For the holes, measure the screw's shank, not its head, and add a little: a 4 mm bolt wants a 4.5 mm hole. If you are matching holes that already exist, set the spacing by hand rather than leaving it even, and measure centre to centre.
That half millimetre is a guess at what your printer does to a hole. Print the Tolerance Kit once and it becomes a measurement instead: the screw list then opens with sizes worked out for your machine and the spool on it.
| Material | PETG, or PLA |
| Layer height | 0.2 mm |
| Walls | 4 or more |
| Infill | 40% and up, gyroid |
| Supports | None |
| Orientation | As downloaded |
It arrives lying on its side, which is the whole trick: every layer is a complete L, so a load at the corner presses along the layers instead of prying them apart. Stood up the other way it would snap at the corner.
Printed plastic is not steel. A 4 mm bracket 25 mm wide will hold a full bookshelf; it will not hold a person. Strength comes from width and from the brace before it comes from thickness, so widen it before you thicken it.
The holes print sideways, so the top of each one comes out a touch flat. If a bolt has to be a close fit, run the drill size through it by hand once.
The geometry is a small Javascript module. It runs in node as happily as here if you would rather script it.