Italian maker “MadSimon” sent us info and a link to this video for his 3D freehand drawing rig. He explains:

It is an experimental DIY peripheral that behaves like a “3D pen.” Just hold the tip of the robo-arm, and act like you’re drawing, pressing keyboard buttons to lay down points and lines. The advantage here is that you can draw in three dimensions, thus creating solid figures. The trimmers placed at the four joints act as cheap, simple angular sensors. A Microchip PIC16F818 converts the signal from the trimmers into digital data, and sends it to the PC app through a parallel port. The software then makes sure the virtual arm follows every movement.

As for the mechanical part, the last two joints are made by the trimmers alone. The trimmer you can see being held by a fork is reinforced with a bearing keeping its rod in place. The base sensor isn’t visible, it’s hidden under the big car bearing at the bottom which holds up the whole thing. The drawer is usually powered by a 9v battery, but in the video, I’m using a converted PC power supply.

The 3D software was programmed using open source library Irrlicht. Firmware for the PIC microcontroller was programmed with MikroC.

3d Freehand Drawer

Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor for Boing Boing and WINK Books. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.


  • TimC

    Looks like with a few software changes this could be used to gather coordinates – a 3D coordinate measuring arm. Everyone seems to be enthusiastic about the laser 3D machines, but I would really like to see someone build and document a 3D arm after MadSimon’s idea. Good job.