Help with Create a Sieve with Procedure

Hello, I tried to create a sieve like in the mod Nhilo, for my project, I have the block myself but I can't get the procedure right and wanted to ask if someone here has already done something like this..

In principle, the sieve should be right-clicked with e.g. sand, and the sand is slowly sieved and ores should come out randomly. But you should also be able to change the grid to increase the chance of random ores..