First, some credit where credit is due: This is for the perennially popular Honeycomb Storage Wall by RostaP, without which none of this would be possible. I also shamelessly lifted the design idea, although did not use the model itself, for the sunglasses holder from DusBus. So jury's out on whether or not this is a “remix." I owe this either way to the Secret of Show Business. You know, find an act that works… and steal it.
So what's the deal?
Well, I have a pair of motorcycle shades that are too deep for the aforementioned sunglasses holder. So I knocked together this model in FreeCAD, which has easily adjustable length.

Just measure out the depth of your sunnies when folded, from the outside of the bridge of the nose to the outside of the backs of the arms. Plug that in to the single cell found in the attached “Parameters” spreadsheet:

And then Robert is the brother of your father, you'll get your very own custom length sunglasses holder peg.
This just shlorps into one of the “insert, empty” pieces for the Honeycomb Wall. You can glue it if you like, but I have not yet had to bother.
The author marked this model as their own original creation.