Thanks all for the inputs.
Once I will visit my friend's we will deal with the power problem; right now I am thinking about using 9V battery pack (rechargable maybe?). As for solar panel, since all will be inside a close (I assume) building, with no/really few windows, I don't think it's duable but correct me if I am wrong.
As for the ESD protection, a good layout would be to keep all the HX711 and the arduino inside an enclosure with only the cables from the load cells coming in right? Should I keep the battery pack in a different enclosure?
Lastly, any recommended program to try a simulation?
Thanks a lot for the patience 
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