Filament spool scale

I use airtight cases for 3DJake’s 250g filament spools. But the problem is to know how much filament is left there. So created a kinda smart scale, that tells me the amount in percents.

The case is designed to be attached to the top right part of the Prusa i3 printer’s frame by using longer M3 bolts and nuts. A load cell is mounted to the case with two about 15mm M5 bolts and the arm is attached to the load cell with two 15mm M4 bolts.

Parts used: