I'm building a gantry multipurpose CNC machine (not my first build) and got all the mechanics of that squared away no problem. What I am looking to do is this:

I want to buy a 3d extrusion print head, and simply lay-out melted plastic traces over a blank copper clad board. Switch tool to spindle, drill the holes. Take the board, plop into ferric chloride and etch away the remaining copper. I could possibly change the bit again to mill away any plastic areas where soldering required on the lead pads. Do I need to apply a current across the blank copper board so it heats up and accepts the melted plastic for just one simple layer or can I get away with a cold board?

Can anyone who already owns a 3d printer with that extrusion head advise me on any part of this which may go wrong? I watch videos of how 3d printer works and got this idea. Is ABS best plastic to use - or can I get away with a quick low temp semi-wax type of material (I dont know everything that exists but I feel that pretty much anything can be spooled, heated, and plopped around a positioning system.

Any advice appreciated thanks.