The solution albeit with a bit of work is:
- Select each Layer and Take a snapshot within Acrobat Reader to maintain same sizes.
- Paste each snapshot at a time into Lightburn
- When you have all layers in Lightburn select each one trace and set to a separated Cut/Layer.
pcb_1.lbrn2 (134.7 KB)
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Also there is a javascript to auto separate Layers.
Separate, Show & Hide Layers in PDFs with JavaScript | Apryse documentation