How can I manage one component if I always need a fixed quantity, regardless of the quantity of the BoM holder product ?
Let me explain further: the BoM describes how to produce an item by weight, or length, so If the work order indicates to produce X Kg or Y mt of that Item (maybe a cheese, a sculpture, a flag a table), I need some component's quantities related to the item's quantity, but other components have fixed quantities.

EXAMPLE:
In my BoM I have :

1 unit (Kg) of cheese needs 3 lt of milk, 10gr of rennet, 100gr of salt , 1 box. BUT if my work order contains 3 kg of cheese (a single cheese of 3 kg), I need 9 lt ok milk, 30 gr of rennet, 300 gr of salt and ONLY ONE box

1 unit (mt) of flag needs 0,5 mt of color1 fabric, 0,5 mt of color2 fabric, 10mt of wire, 1 pole. BUT if my work order contains a 2 mt flag, I need 1 mt of color1 fabric, 1 mt of color2 fabric, 20mt of wire and ONLY ONE pole.

1 unit (mt) of custom table needs 1 mt of wood, 0,5 lt of paint, 4 legs and 16 screws.
BUT, if my work order contains a 135 cm long table, I need 1,35 mt of wood,  0,675 of paint and ONLY 4 legs and 16 screws

How to do this?