I got the basic Idea and I have shurely no problem with calculation maybe with understanding

but you mean I have to test all the products at home(that is my business then, when I understand you right) and maybe I sell it to some customers ^^ and if not it was only a failed test so nobody can fuck me for that?
Do I understand you now right? So I just write down all my bigger cost-posts as needed for company because I maybe will sell that. Ok that makes sense, thats then the backfire of having a monstroses stupid burocracy like we have in germany that you can never control all that, what I use more for private stuff and what I use more for other stuff etc.
Did I understand you now right ^^