Alex requested a "quick and dirty prototype" for his Opentherm JeeNode interface. He has more details on the "substance" here and here. I just made the boards, it is all his design (boards plural, the first one was wrongly mirrored, b.t.w. it is the wrong one you see on the pictures).
I followed the usual toner transfer method, and just works, HEMA photo paper is the best! The second board is not so pretty.... but at least it is correct (no photos of this one though).
The schematics are on Alex's site but here's my second try at the schematics also:
Here a detail of the board where you can see some "over etching":