FAB 3000 (Version 8) is an excellent tool for converting ODB++ back to simple Gerbers and NC Drill data for manufacturing. Please perform the following:
1. Import ODB++ into FAB 3000 (menu: File / Import / ODB++)
2. Export Gerbers and NC (menu: File / Export / PCB (Gerber/NC)...
That's it, you will have a folder which now incudes all Gerber and Drill files from ODB++.
Since the ODB++ has been loaded into FAB 3000, you can also export more formats such as IPC Netlist, DXF, IPC-2581, 3D STEP, etc.
--- For 95% of people that's all which is needed.
ODB++ surfaces are not directly supported in Gerber files. By default FAB 3000 will convert surfaces into polygons (G36/G37) with various composite levels (paint/scratch). Depending on the surface complexity sometimes there can be converted polygons with hundreds/thousands of composite levels. This is completely fine and meets Gerber format specifications, however some older EDA software tools cannot handle multiple composite levels.
If you wish to remove composite levels completely use Cutlines - see below:
When importing the ODB++ check the option "Convert Surfaces to Polygons (with cutlines)"
To resolve the issue now, during ODB++ import select the option "Convert Surfaces to Polygons (with cutlines)". This will also make more compatible and simple Gerber files with less composite levels used in complex surfaces. https://support.numericalinnovations.com/support/discussions/topics/14000002354
Important: We recommend that you leave "Convert Surfaces to Polygons (with cutlines)" Unchecked. Why? Cutlines makes the resulting Gerber files more compatible with all tools in a design flow (limiting composite levels), however Cutlines add additional data to your geometries which can slow down processes like DFM Checking, etc.