The only thing I'd change is, coins aren't random enough unless you get a real random coin, and since the coin is being used for the same operation over and over it compounds. Use another casino die and say odd = heads and even = tails. And, instead of saying "this die is the coin", make the last of six (right to left and top to bottom" count as the coin, this randomizes any loss of entropy a little bit more should one of the dice have a significant bias.