I have a large tray that I used for wetting paper for printing, but I had a hard time finding some kind of screen to put on top of it. We ended up taking apart an unused baby-gate and I used on side of it over the tray. It worked okay, it's major downfall being that the ice can fall through the large holes. I would suggest a window screen or a shelving rack with smaller holes.
So, first you soak your fabric in a soda ash solution.
Then the art here is in how you fold the fabrics. I tried several different ways, even just bunching it up. Then I put them all on the screen close together.
Then pile on ice cubes.
Then sprinkle on the dry dye pigments. I used three different colors.
Isn't that beautiful!
I found myself sitting there staring at the beautiful colors as the dyes ate into the ice and started to melt onto the fabrics.
Then I realized I was sitting there watching ice melt and I got up and went to do something productive.
The next morning, the ice is melted. I rinsed out the fabrics and hung them up to dry.
Depending on how you fold them, you get some interesting results.