FUN WITH AQUATINT:
This quick little sketch should encourage you to make a dandy unpatented rosin dust chamber from a cardboard box.
The baffles at the bottom are folded corrugated cardboard. They will serve as a platform to hold the plate while allowing the rosin powder to settle to the bottom of the box.
The door is just a cut-out flap which will fold open while you insert and retrieve the plate. Glue a piece of mat board to the outside of the door to act as a baffle which, if closed tight enough, will help keep dust inside the box (some dust will still manage to seep out). You should rig a method of keeping the door shut -- for example, wrap a bungee cord around the box. Seal all seams with tape.
HOW TO USE IT:
Pour in some powdered rosin and secure the door (with the bungee cord or whatever).
Turn on some dance music and boogie the box around to stir up the cloud of dust. When you tire of that, set the box down, open the door, insert the plate, close and secure the door.
Wait while the cloud of dust responds to the pull of gravity and settles to the plate.
Remove the plate carefully (the door is specially designed to keep you alert). Inspect the coating of dust and decide if it is thick enough. If you want more dust, you can boogie on some more.