The original latch arm/cam design is awful - you scrape your knuckles trying to open it, the cam moves flat against the box when you try to push the cam to it, rubbish!

So I made the arm longer and added a sticky-out bit so you can get your finger under it to open it, also made the screw hole a bit bigger so the screw just goes through it rather than biting into the plastic.

This makes things a bit better, but honestly, I gave up with the whole thing eventually as I managed to split the ~11 hour print screwing it together (oh and if you want to use lock nuts then you'd better get 25mm M3 bolts not 20). The hinges aren't great either - too tight, plus I got some 2mm silicone tubing to put in it and its too loose, had to glue it in place.

The only good thing about the original design is the lid.