The shelf support pegs in my bathroom vanity were always falling out, so I modelled and printed some that would fit a little tighter. They seem to be working so far.

The peg has a diameter of 5mm

The platform that holds the shelf was around 2mm thick on the original clip. In my design, I beefed it up to 3mm. I've included the STL that I used and a thin one that sticks to the original 2mm thickness.