Holy heck you mixed up a BUTTLOAD of plastic there. When I was hardening my suit, I would mix up about a third of that amount to slush around the inside. This stuff goes VERY, VERY, VERY, VERY, VERY far.
Also, when you have a huge mass of the stuff (like in the cup), it will harden faster. It hardens like any other resin: the hotter it gets, the faster it cures. So, if you mix up a lot, SPREAD IT OUT!!! FAST!!!!