After successfully reverse engineering a two-layer board, I wondered: can I do the same with a four-layer board? I chose a four-layer board with larger components: SMD resistors and SMD capacitors no smaller than 0805. The board is automotive-grade: for AdBlue pump control.
For this project, I used Sprint Layout 6.0 — I didn't use Inkscape for the design.
Unfortunately, so far I haven't been able to locate the files I created with Sprint Layout 6.0.
I'm attaching photos. The board is 4-layer and quite thick: it took quite a bit of sanding to get through it :) .

Layer 1 - TOP , with components.

Layer 1 - TOP , with components and with the component designations.

Layer 1 - TOP , with the component designations.

Layer 1 - TOP , without components.

Layer 2 - Inner layer.

Layer 3 - Inner layer.

Layer 4 - BOT , with components.

Layer 4 - BOT , with components and with the component designations.

Layer 4 - BOT , with the component designations.

Layer 4 - BOT , without components.

Components : TOP and BOT , wthout picture : component designations.

Components : TOP and BOT .

Components : TOP and BOT + component designations.
Vladimir Todorov
Adem-ADATEPE
Henrik Alexandersson
Dave's Dev Lab
carbono.silício