CirCut - the short story: With a ~$270 machine I can produce one and two sided PCBs inside of a few minutes - much faster than any other method I know of. The "few minutes" is from EagleCad output to a finished, etched copperclad PCB ready to be soldered. No messy etchant and no mods required to the machine. I'd like to start sharing this info in hopes the corpus of knowledge and utility will grow....if there's interest.
I'm not talking about cutting a solder or etch mask or using an etch-resistant pen in an XY plotter as has been discussed in this group. I'm talking about a ready-to-use PCB in a few minutes with no more than your PC and a hobby paper cutter. There is some hand-waving here....but not much :-)
I'm fairly new to this group but not new to DIY PCBs, having sweated through most of the rapid protype production of PCBs for the past few decades. I did a web-wide search and a search on this group but can't find a similar technique so sorry if this is not new. Some folks at MIT Media Lab use a vinyl cutter to cut copper foil with adhesive. You peel the circuit pattern off its backing and place it onto a substrate for soldering. My technique is different.
I started a few years ago making a PCBs with a Cricut CNC paper cutting machine by actually cutting through the copper cladding and isolating wires pads and vias, much the way mechanical etching does (see Yahoo group PCB-GCODE and the cover photo to this group). T-Tech, LPKF and Accurate have desktop milling machines that do this....for a pretty penny. A big problem with the Cricut was that there was no "drag knife compensation" - knowing where the swivel blade will follow behind the XY cutter so it can predictably lead it and not get funky lines which are no good for small traces or small pads. I had to limit my PCBs to ones with fairly fat traces and lines. But it still worked. A few months ago I discovered a new low-cost CNC paper cutter that solved most of my problems and now I'm producing fairly nice looking mechanically etched PCBs. I'm sure there are warts to be found but they haven't surfaced yet. Some of the cuts are not absolutely straight so this limits the smallest trace width to around 10 mils. I am now starting to document these findings, shortcomings, equipment sources, workflow, etc on my web page.
Some other things I am presently exploring is for this low-cost CNC machine to also automatically drill the PCB, label parts placement and add solder mask. I'm not sure how successful these efforts will be but it shows promise as I've been able to do all these things to some degree so far.
Please see
http://research.microsoft.com/en-us/projects/papercutterpcbs/-mike