Finally got around to try this out. I made a dice tower out of card board box. Took about half an hour, using X-acto knife and a metal ruler... that's it. No tape, glue, or anything.
Here's the top, looking down. I only put in two boards for the dice to bounce off of.
At the bottom, I cut an opening for the dice to roll out. It works with all size of dice. For first one, I think I did okay.