First, Eisen wanted to make a small prototype for the potion-distillation system. After all, he wanted to make sure it properly worked, and supersizing it afterward would be a rather easy thing.
And like that, he could have a mobile version to use for himself as well, to make his potion-making easier. So, Eisen quickly started to make the bowl for the grinder, and made it out of simple steel on the outside, layering it with a thin layer of mythril on the inside. This was so that Eisen wouldn't be wasting as much Mythril as he usually was up until now, and then moved on toward the most important mechanism. The automatic grinding.