Over the years, I have accumulated boxes of random screws that I was too lazy to sort. Primarily because figuring out the size and length was too tedious and time-consuming. I designed this little tool intending to simplify that sorting process.

In the center of the Tool is a V-slot and metric ruler. Just lay the screw in there, set the screw head flush, and use the metric reference on the ruler. Markings are 2mm apart. This tool can measure screws up to 50mm or longer if you're clever ;)

On the left side of the tool are four heat inserts for checking threads M2-M5 ( I used these heat inserts: https://www.amazon.com/dp/B07MWBJB67/ref=cm_sw_r_cp_api_i_06G-Db8N6QN3N). The design could be easily modified for whatever type of heat inserts you want to use. I am including the STEP file for anyone needing to modify the holes. The heat insert depth I used is 6mm; after that, the holes open up to make room for any excess melted plastic. It can be challenging to get the heat insert in and keep the excess plastic out of the way of the threads. I’ve found putting a screw through while the heat insert is still hot allows you to align the heat insert and push excess plastic out of the way.

The uploaded photo with the two-color print was a single STL modified in PrusaSlicer using modifier slabs. In addition to the STL, I have also uploaded the two-color 3MF project file in case someone wants to print in multiple colors. I also included GCODE for the Prusa MK3S/MMU2S using PLA in 1 and 2.