This tiny pen plotter is not only adorable, it is cheap and easy to build as well.
One of my favorite DIY experiences has always been making something that makes something else. This project is a perfect example of a cheap way to do exactly that. A $20 pen plotter is not only a fantastic learning experience, once you're done it, can make other things, in this case, drawings.
All of the components laid out. (Source: Plotterbot.com)
This project comes from Plotterbot.com, which makes a few different plotter bots generally of higher quality than this one. This little project, however, is so thoroughly documented, it serves as a great lesson in design. That, and it's just really cute and simple.
The Tiny CNC is mostly 3D printed, though admittedly at first glance I thought it was scavenged from a CD-ROM tray. There aren't many parts, but it's also only two axis currently. This means that the pen does not lift. However, the z-axis addition is pretty high on the list of immediate improvements, according to the website.
It seems like Plotterbot.com occasionally has sets of the plastic parts available, so if you don't have access to a 3D printer, all hope is not lost. Plotterbot would probably love to see how other people implement the pen lift mechanism.