I recently printed this nice Flexi glasses case from user @rorys3D on Printables. I was looking for a nice case for some cool glacier glasses I got recently and this design fit the bill. It's a single-piece, print-in-place living hinge design, so despite its curved and mostly-hollow shape it is very easy to print.

I think it's designed for smaller reading glasses, so I scaled up the X and Z dimensions by 150% to fit my glasses. The width of the case was fine, so I didn't rescale the width axis (Y axis in this case) at all. The Printables page strongly recommends scaling up those two axes (X & Z) together to ensure all the hinges and snap mechanisms still work, and in my case they did!

I printed the file in gray PETG on a Prusa MK4S at the MIT Metropolis makerspace, which took about 8 hours with this material and the settings recommended on the Printables page (3 perimeters, 0.2 mm layer height).

Here's how it came out!

The file prints flat in a single piece:

It looks like I estimated the 150% scaling pretty well! I maybe could have gone with 140% scaling instead but this is a fine fit.

The bottom hinge snaps really firmly into the sides of the case. There's a really nice snap sound when this snaps together. I had to push pretty hard to get the snaps to engage on both sides so I feel confident that it they'll hold:

Here's how the case looks with the bottom hinge folded over and both snaps in place:

The top hinge also folds over and latches in place nicely, although this latching mechanism is intended to be closed and reopened repeatedly (unlike the snaps for the bottom hinge).

Here's the case with the classes inside! I'm taking these on a trip soon so I'll get to see how well the case holds up.

Based on a comment on the Printables page, I might add in a soft fabric interior with some spray-on adhesive in the future. The PETG doesn't feel too scratchy, but it'd be nice to have a a softer material on the inside to protect the lenses.