I’ve got various tools that I have been using as a dizz, but there have always been shortcomings. I’ve found it difficult to get the holes smooth enough in wooden ones I have, even after quite a lot of use. I also use a big coat wooden button, (same problem with the holes), and the plastic button I used snapped in half.
The wooden coat button is nicely concave, and I like that feature. When I saw the curved brass ones made by Majacraft I became covetous. So imagine my joy on receiving one from my son as a present at Christmas!

Apparently the two smaller holes (1.5mm and 3mm) are for fine and coarser wools and the largest one is for colour blending fibres as you ‘dizz’.