As a really bad 3D designer, I have created the first version using Tinkercad, and for this new version I have decided to use the very cool Shapr3D software to draw 3D parts that I want to print.

When I had to print parts that had to fit into each other, I was faced with a technical reality:
At the beginning, I had simply transformed the part which was to enter the other into a "hole" to create the hole. But in fact, you need a margin of tolerance, otherwise it won't fit.

And this margin of tolerance, I suspect it depends on the 3D printer and probably on the filament and its fineness, the nozzle, the quality set, etc.

In any case, I started to spread the holes a bit at random, and then finally I created this gauge to find out by how much precisely you have to spread the holes in a print for the parts to fit into each other.

This model allows you to print a part of which the part to be nested is 1cm on the side (a square therefore).

And in the gauge, the holes are linked with 0.1mm more each time, from 0.0mm to 1.0mm.

On my prvious Markebot Method for example, the part fits quietly with a gap of 0.4mm. At 0.3mm it rubs a bit, and at 0.2mm you really have to force it.

On my new Bambulab X1C, the rubbing part starts at 0.2mm and you can force with 0.1mm tolerance…

In addition, I added small plates whose orientation changes every 5 °, which must be printed without support, to see with what quality your printer can print angles (this will allow you to know the limits without support) .

And finally, in front of the gauge, I have added thickness testers, starting from 0.5mm to 8mm.

Finally, it has been designed to be printed in multi-color, as the Bambulab allows.

Hope you find this useful.