Please allow a little showcase. I guess this has been done before, but I wanted to see if it was possible to turn a hand drawing into a reasonable 3d printed model. As an additional constraint, I wanted to do it using mostly my own tools.
I started by drawing my initials "CA" by hand using a black marker on a white piece of paper (A4), the characters were outlined as shown in the image below. Next it was scanned using a cheap flatbed scanner, giving me a BMP file. I used IrfanView to crop the drawing and decreased the color depth to 1 bit per pixel, plus I flood filled the internals of the characters to make them all black. Finally inverted the image to make the initials white on black and save to PNG.
After "a few more steps" I got this, printed with my Simple Metal
To make the hand drawing into the print as shown, I used a new program I wrote to detect the profiles around the characters. It is able to properly see the difference between outer contours and inner contours (holes). The character "A" contains a hole for example. After a bit of processing (a couple of seconds) the contours are identified and the information exported as an Angelscript CSG source file. The generated code lists all the outer contours as one group that is unioned together ("plus union") and the inner contours are also unioned ("minus union"). The minus union is subtracted from the plus union and voila the result is a 2d profile that can be extruded, for example using rotation as in this case.
I have also tried this with other data, for example the classic Ford logo, and it works fine too: