I have a specific need and would like some input :
I want to trace an outline with a very odd shape, specifically lots of overhangs. I am also alone, so I can’t rely on another pair of hands.
I was thinking of 3D modeling a carpenter square with a hole at the corner so I could put a pencil or pen there. But I am afraid I won’t be able to adjust the pen/ pencil tip position so it rests at said corner. Do you have any insight?
If you own a flat-bed scanner, and it’s small enough to fit, You can get an outline of the shape by putting it on the scanner and doing a scan. Then you can print it out if you need it to be on actual paper.
When I want to make something that attaches to something else, I often use this trick to get a 2D outline for my CAD program to work with.
No, the thing (A LARP foam wakizashi) is way too big to fit on a flatbed scanner. I also thought of taking a picture than drawing the outline, but I don’t have good enough resolution at a far enough distance to avoid lense distortion.
Are you wanting to 3d print a model, or produce a drawing of its outline?
In the end I need the outline to 3d model the whole object because I want to do a sheath for the sword. If I could accurately 3d scan I could be interested but I don’t have the tools or setup for it.
So instead I was planning to use a paper version of the outline traced on grid paper so I can transfer the shape.
It’s what I have already done for my tanto.
I think I’d hang it on a wall, if possible with a grid of some sort behind it. If no grid, then a few straight edges with markings on them. Then, stand back and use your phone/camera to take a photo. That can then be loaded into a cad program as a background image. FDM 3d printing is used in rapid prototyping, so don’t fuss with the exact shape to start with. Print a thin outline, allowing whatever margin you want to fit. If you print in lightcoloured pla, you can mark deviations on the print, then adjust the the design to suit. I would guess the outlines are basically large radius arcs.
I use openscad, so I would then increase the thickness of the drawing of the template, then difference that from whatever external shape of the sheath that I desired. It is not difficult, possibly just tedious.
If you want to trace around the object, then you need to print something like a carpenters square, but with a hole for a pencil/pen going to the corner, such that point of pen/pencil is exactly at the corner. Make the stock of the square thick enough so that the blade can be held vertical when tracing the item. You will have to fix the item you are tracing fairly secure to the paper/flat work surface. HTH.
It’s exactly what I was aiming, the question is the pen/ pencil that fits
Measure your pencil diameter, and make the hole bigger. You can wrap tape around the pencil to get the fit how you like. You can push the pencil down with your index finger, or use elastic band. If it is going to be used a lot, then design something better, involving sliding tubes and springs 
. Do not aim for precision with this, you will correct the drawing after the first quick test print, but it should be accurate enough within a couple of mm., and you can measure the object to check.
