I have this:
but slightly larger. Got it off TaoBao for a few bucks; it's designed specifically for keycaps, so the lid closes just shallow enough so that the caps don't spill out if you tilt the case over--except for DSA caps. Those fall out anyway. The lid doesn't snap shut, so it'll slide open if you tilt it on its open end.
I use this one in the pic to store Esc's and novelties, and the larger one to store artisans. Same square dimensions, but it comes with extra grid pieces to allow for wider caps, like 1.25u and 1.5u caps. However, it doesn't fit large artisans too well, like the SVC girlDC cap or some of Krytone's larger works. May get the Dauber one in OP's link to see if it'll fit larger caps better.
Been meaning to put up a pic with the artisans lately...