But in my case it was already good enough out of the box. If you need extra fine results you can calibrate your scanner using some part of known dimensions and calculating the scaling coefficient. The results should be a precise match unless you scanner software screwed up DPI setting somehow. For PNG the DPI should be saved in the file, but to make sure – you can draw a line, see how long it is in mm and compare it with the ‘real thing’ using calipers. Now import (File->Import) this stuff to inkscape. Here’s what I got after scanning and playing with sliders: If the cardboard or paper isn’t quite white (Like the one I took for this tutorial) play with contrast and brightness sliders to make it appear whiter.

I picked 300dpi, but it’s mostly a matter of taste and performance.

Preferably pick PNG for less compression artifacts and a relatively high DPI. I prefer to trace it to avoid scratching the scanner. It all depends on the color and material of the part and the desired results. Or you can put the part directly under the scanner. First we’ll need a piece of paper or cardboard and pencil and trace our shape. As a small example I’ll clone part of my archery fingertab. This technique can also be used to reverse-engineer complex PCB shapes to aid in creating custom enclosures. You may use this for any complex shapes that are too tough to measure using calipers. This small tutorial will cover how to clone complex 2d parts with a flatbed scanner, inkscape and freecad.

Freecad 2d tutorial