This is a topic that interests me. The most useful sounding site I've found so far is this one <http://www.thinktink.com/stack/volumes/volvi/pcbproto.htm> IIRC, they recommend drilling your boards before etching so that you can use the hole locations to help with your layer registration. They also have an interesting ink and electroplating system to create plated-through vias. (As an aside, I found another site one time where a fellow had replaced the pen in a plotter with a drill and was using it to drill boards with an Apple II(?) driving the thing. <http://rich12345.tripod.com/PCB/> It would be an interesting project if one could make it interpret Excellon drill files.) However, the information on greater than 2 layer boards is thin. They seem to imply that you can etch seperate thinner boards and then laminate them together, but there's no detail on what kind of board would work for this. There's an obscure reference to not fully cured fiberglass or some such. The implication is that, e.g. one could make a total .062" thick board with four layers out of three boards laminated together--perhaps three .020" boards. The two outer boards would be double sided circuit boards and the center would be a separator with plated-through vias and "doughnuts" at the plated-through holes to make contact from one board to the next. I'm curious about what one would need in terms of board or additives to laminate multi-layer boards together. A standard fully cured board isn't going to stick, I don't think. Building multi-layer boards out of raw fiberglass/epoxy mix and copper plating it oneself does not sound like a viable home project. At least, not for me. Jeff Walther