I just use a coffee filter. Serves double purpose too, for when I'm done smoking I empty the dottle there and the dirty cleaners, then I ball it all up and into the wastebasket it goes. Easy.
You kids and your goofy new fangled ideas! Trays? Caddies? Coffee filers? Step back and take a breath. All you need is a good old cloth rollup pouch. Unroll it and you have access to the tobacco you keep in the pouch and a handy flap that will catch your overflow. Get it together!