With what ever requirement we disccussed till now my feeling is variant configuration no where fit for it, there is option to use batch management but agin i can see if your second ,level materials use batches you need to use batch determination at first level to consume this batches received while doing GR's.
Also as you mentioned every finsihed component is one time use and after that it may be discarded only components which are consumables are reused.
My suggestion is look for simple solution like below.
Maintain a purchase order text in material master , put instreruction like " Thread colour RED" and once PR is generated and converted into PO this text will be copied into purchase order and will be useful for purchasing department.
You can open a thread in MM forum asking for a frugle solution to cover this requirement. I belive there are many text element availble in PO's and you can find a way to fetch item text from BOM in PO instead of going for VC or Batch management.
Please chekc and reply.
Thanks
Ritesh