3D printed PCB

How to print a plastic PCB.

Make a circuit in Fritzing(or your favourite PCB program that exports SVG or PNG).
Make the traces a little larger than default.
If you're using Fritzing, you'll need to convert the SVG to a PNG. I used Inkscape.
In the openSCAD script, change the file names to suit your project file names.
Also in openSCAD, resize your circuit board to match the size in Fritzing.
Magic.
Print the top silkscreen on to a sticky paper and stick it to your PCB.
Using the legs from your components or spare wire, bend and trim the wires in the grooves of the traces and solder.

Not as robust as normal circuit board, but good for small batch or proof of concept.

UPDATE:Jan2019
Added a zip file to load the png files. Thingiverse drops the image files and formats needed for OpenSCAD to work.

UPDATE:Oct2020
Issue with png not working with surface function. Used image software to save the png as a bitmap, then back to png, then it worked.