Homemade circuits are a natural complement to 3–D printers in the renaissance of garage tinkering.
With the rise of 3–D printers, homebrew hobbyists can now make enclosures for electronics like Ardiunos. But until recently, those hobbyists still couldn't make the actual computing components––there's no cheap and easy way to print circuit boards. Unless of course you have an inkjet printer and some time to hack.