Hi korp-audio
You can achieve what you want using ATUM Product Levels.
You can create BOMs as the products to include in your Kits. You can add each BOM to one, two, or as many Kits as you want.
You can also set the BOMs you want to sell as "Sellable".

Only BOMs with this option enabled will be visible from the front end.
You can read the entire Product Levels documentation here.
Best Regards,
José Andrés