The documentation talks about semi-finished products.

https://www.odoo.com/documentation/15.0/applications/inventory_and_mrp/manufacturing/management/sub_assemblies.html

But what if you want to use such 'composite' boms at a subcontractor.

Say i have a product 'Steel table', it consists of legs and a table top. So it is a BoM, subcontractor, and i supply the products to my subcontractor. All is fine.

Now i want to also create a product "Painted steel table" with 3 colors.

So i create a BoM for these variants. With a steel table inside and the product has the cost for the spray painting.

Now the subcontractor can 'prepare' steel tables. and when an order comes in for a 'blue' one, it can take one from its stock and spray paint it.

I don't manage to this to work automatically. So when i order a 'steel table colored blue' it will automatically make a subcontractor/manufacturing order for the normal steel table, in case there are none in stock with the subcontractor location.