Module Keurig Holder Insert

I had been storing my k-cups on the inside of my cabinet door in some foam that I had cut out. I wanted to upgrade my storage and really liked the design of these (https://makerworld.com/en/models/1605970-modular-keurig-pod-holder-infinite-layout#profileId-1693428), plus they fit great in my door dimensions. I realized after I had them installed, however, that opening the cabinet door caused them to all fall out of the holder since they're just loosely sitting in there. They'd be great if they were attached to an unmoving wall but not so great for a swinging door. I still wanted to use the holders, so I made some inserts that fit in nice and tight into each hole and the k-cups sit much more snugly inside.