Many years ago I bought a very sturdy printed circuit board from an American tube audio designer called John Broskie. He runs a site called Tubecad.com. His Aikido amplifier design is probably one the most popular concepts among DIY audio equipment builders. It is extensively documented, incredibly adaptable and almost endlessly modifiable. There are many different versions of these PCBs available so you won't run out of options any time soon. Anyway, I bought the PCB and then just forgot about it for several years. I don't even remember what the original idea was, but I had suitable tubes and almost all the other components, so I finally decided to build the amp.
This is a preamp/buffer and a headphone amp combination using 6CG7 and 6H30 amplifier tubes and a GZ34 rectifier. The power supply components are mostly recycled from old equipment and the case is mostly built out of recycled materials from the scrapyard.