So I made my first attempt at SMBC using egg whites by EggBeaters, which I now know to be a mistake. The meringue didn't set up and I am left with a soupy egg beater/sugar mix. I decided to save the butter for my next attempt with real eggs--much better!

Should I just throw it away, or can it be used for anything? Can I make a thin royal icing out of it? I am working on a cake that I was going to make some for "glue".

Anytime I tried IMBC with eggbeaters, it did not work. For me, with IMBC it helps if the egg whites are at room temp. I use pateurized egg whites at room temp. Good luck.