You already make a whole load of original stuff with 3D printers. Next step: turn those same objects into smart objects of sort. If the kind of things you design, however, aren't quite sized to hold conventional circuit boards that will let you turn them into self-functioning automatons, you'll need to make your own. The Othermill is designed to accomplish that.
Made by Otherfab, it's a desktop mill that lets you make custom circuit boards cheaply and quickly (1,000 mm/min traverse time). Whether you want to add fancy lighting systems in your plastic robots, auto-tweeting electronics in your nanny cam, or custom digital sounds for your effects pedals, this should let you print out the boards that will get it done.
The Othermill is a desktop-sized 3-axis mill that can be used in small workspaces, as well as carried around for easy transport. Otherfab claims its compact enough for use at home, all while being precise enough to use in high-level electrical and mechanical prototyping. How precise? The machine is specifically equipped to cut 10 mil trace and space on non-toxic FR-1 PCB stock, allowing for really detailed boards. It's designed to work with minimal noise, too, so you can cut late into the night without waking up the kids.
While designed with PCBs in mind, this isn't just relegated to cutting circuit boards, either. Instead, it's an ertswhile full-featured milling machine, allowing you to cut metal, wood, wax and plastics for other projects, such as jewelry and engravings. As for software, it can work with, pretty much, any CAM software that outputs g-code in arc/mm.
Currently, the Othermill is a Kickstarter project collecting backers. Available pledges to reserve one start at $1,399.