The slats in our shower caddy often let soap fall through; this insert was designed to fit a couple bars of soap, with smaller drainage gaps.

To make it work on a countertop, you could stick on some rubber bumpers to make it grippy, and to give it a little clearance for the water to drain.

I printed in PLA with slightly sped-up Cura settings on my Ender 3 V2 Neo, on a .6mm nozzle. I'd recommend making sure your print speed isn't too high to avoid the gaps I got on some of my walls.

Link to the OnShape model is here, if you'd like to remix!