After the Kodak Helios lens, I've built now a new combination out of an enlarging lens and an old M42 lens.
The enlarging lens is the Schneider Kreuznach Componon 5.6/80mm and the M42 lens is the Exaktar SFX 35.
Once again I slaughtered one of mine M42 lens, but the Exaktar SFX 35 was really very difficult to use. It was very easy to combine the two lenses.
Here're some pictures made with the lens!
Here is a good DIY-instruction to adapt an enlarging lens on a SLR.