In order I work with the order preparation and I want to track the inventory of the material I use in production. (like paper and Ink) They are not all measure in quantity but also in weight.
It sounds like you are in manufacturing. If so, each Product should have a category of Raw Materials, Work-In-Progress, Finished Good. Some also include Labor and Packing Materials in that list.
A related table should exist for Work-In-Progress and Finished Goods. This is your Bill of Materials (BOM) table. The BOM should include the amounts (quantity, weight, etc.) to make one unit of the Work-In-Progress or Finished Good.
You'll likely need to convert measurements. For example, you may buy ink by the gallon but use it by the ounce. I manage this with data and scripting. On the data side, I have two tables: Unit of Measure and Unit of Measure Conversion tables (see image). For example, if I need to convert something from grams to kilograms (the "Start from" portal) or from each to gram (the "End in" portal), I have the data available to perform math.