I would like to build Pumpernickel compressor, but kits are not available for a long time at Musikding.de (https://www.musikding.de/Pumpernickel-compressor-kit). I have a schematic for (probably) similar Campus That Jam compressor, but PN seems to be more refined version. If anyone is willing to share the schematic, well, one can do it here.

I have built one, and it has never been off in my signal chain since.  Well worth it.  Having said that, I don't have the schematic.  It looks as if Julian still has stock on his own site: https://schalltechnik04.de/en/kits

Thanks!