Update 2017-09-18

I've enclosed updated ("v3") versions. As it turns out, you can import STL files as solids into Solidworks instead of just a graphics mesh, lol. I've now edited the original to use extra hinge material, and I've also separated the two halves from the original files so they can be independently (for larger prints).

Upon closer inspection, the reason my from-scratch modelled chest has such a tight hinge is because I forgot to leave some room for the hinge on the bottom side, probably also the reason it wouldn't center properly (on two test prints I made). Will update later to include the double chest.

Original summary 2017-09-15

A modified version of the original model where I found the hinge to detach easily from the lid; I fixed that and added extra support to stop that from happening. Modelled in Solidworks.

Not sure about the dimensions and/or tolerances for the hinge: I test printed this at 50% scale and the hinge is a bit tight and wouldn't center as well as the original. However, unlike the original and thanks to that tight hinge, it does stay closed when you turn it upside down or pick it up by the lid.

I made them separate files so you can add them together in your slicer if you want to print them together, or print them one by one if you want a big chest.

Will update later to see if I can change the hinge so that the lid clicks in easier, centers properly, and is easier to open.