Modified parts to accommodate DIN 934 nuts

The original model was great! However, I did not have DIN 562 nuts; I have A LOT of DIN 934 nuts instead. Therefore, I modified the Top, Bottom, and FrontBack connectors to accommodate DIN 934 M3 nuts. The nut openings are now 3 x 5.7 mm, and you can easily use regular M3 nuts. Additionally, the blade was not always dropping smoothly. I happen to have a box of M5 metal rods with various lengths. The M5 x 30 mm ones were the longest that could fit. Therefore, I modified the knife holder to add chambers for a few metal rods. The metal rods will add weight, making the drop smoother. However, printing them vertically will cause the two parts to close less tightly than before, so I also made the edge thinner.