I made my own egg white powder by beating egg whites til stiff peaks formed, then spreading them onto an ungreased, parchment paper lined sheetcake pan, andbaking on the lowest setting in my oven for 4 hours.
I also found I had to bake it an extra 10 - 15 min and then I turned off the ovenand let it stay in the oventil cool but after that (and chilling in the fridge overnight), it was PERFECT!