An interesting idea for printing a circuit board by Thingiverse user CarryTheWhat.
The goal of this project is to enable the personal manufacturing of simple electronics, especially for Open Source Hardware — with nothing except a 3D printer, your hands or equivalent, and the basic high-technology electronic components (capacitors, motors, transistors, etc — but note that this will also include mass-produced microcontrollers and their shields!). Instead of solder, wires, and breadboards, OpenSCAD generates a peg-board PCB and component holder, and a circuit can be hand-wound together with conductive thread.
This code base is intended to replace conventional etched PCBs, initially for very simple applications. Included is a basic feature set, described in the Instructions. The pictures and uploaded STL files are for a simple circuit which demonstrates these features: a battery holder (I used 3 watch batteries instead of AAs to quickly and easily step up the voltage and save plastic and time), a momentary push-button, a toggle switch, and an LED holder.