Homebrew PCBs

I don't mean to be contrary, but I have used a laser printer to print 
directly on copper and on aluminum. I found that laser printers vary 
tremendously in their ability to do this, but I cannot tell you why 
this is. I believe it was a Lexmark E260 that I first used. I took a 
piece of thin (.005) copperclad and just ran it through like a piece 
of paper. It printed perfectly and even fused!

That said, I have experimented with a number of other laser printers 
and they vary all over the place in this regard. Some won't print at 
all, and many won't fuse. You can easily remove the fuser from most 
laser printers, replacing it with a resistor to simulate the 
temperature measuring thermistor in the fuser. That way you can 
"fuse" the image on the copper in an oven or by using acetone vapor.

If you want to try it, be prepared for a lot of frustration and some 
sparks. Be careful because there is a lot of voltage (at little 
current) in these machines. I would suggest using printers with 
easily replaced drums in case you damage the drum. Rounding and 
smoothing the corners of the pcb help a lot.

Mark