Aisler now provides 6 layer PCB manufacturing:
https://community.aisler.net/t/proudly-announcing-the-6-layer-hd-pcb-service/1701
They are more expensive than JLC or PCBWay, but they are located in the EU (actually less than 10km from where I live) and they are fast, nice and pretty open source friendly.
Finally got around to do day 1 of #adventofcode https://github.com/root42/aoc2022/blob/93f1a0054a1749b1485e551d91df549a6eed7a2d/src/aoc2022/core.clj
Not happy with the parsing, but it works! #letscode #clojure