unfortunately it stopped working for me after about 25; some kind of bug. i could no longer drop new things onto the canvas; they were not "droppable."
This happened to me immediately after dropping the first two things on the canvas. There was a message in the console from their drag-and-drop implementation about some variable being undefined. It seems like they don't handle long latencies gracefully; the assets took more than 2 minutes to appear. (Before that, everything was just a boring beaker with some text.)
clearing the canvas had no effect.