Homebrew PCBs

I showed these pictures to a friend who had tried hacking an R220 and 
his reply is that it's great, but he doubts that it is possible to get 
the registration close enough to do double sided boards. I'm curious if 
you have any reply to that.

He uses unmodified inkjets to print transparencies, aligns them as a 
set, then uses a vacuum table to hold them on a pre-sensatized board 
while exposing under an UV lamp. He says he regularly gets 5 and 5 and 
is happy to be able to do double sided. 

I think a possible solution is to purchase thinner than normal single 
sided stock, etch seperatly, and then bond the two with the backing 
together and the copper sides out. No registration problems because the 
registration is done after the etch. Someone else had described this 
here in more detail.

--
James.