*only*12-meter boards, it is a much simpler optimization.

Have you started trying to design classes/data-structures for this, or started to work on the algorithm, or found an algorithm somewhere you think you can adapt ?

Please show your code.

This CodeProject article contains, I believe, a C# example you can adapt for your project:

C# Bin Packing - Cutting Stock Solver[^].

This CodeProject article might interest you as well:

Rectangle Tiling Algorithm.

There's an open-source C# cutting optimizer, Cut Micro, here: [^].