Expandable foam learning curve

Ooookay...bit too much foam used in the first and last skulls. Foam expanded and bubbled over within about thirty minutes of setting them up. Glad I hadn't waited until after work and took a quick peek. The second skull--the one with the experimentally less foam--appears to not be bubbling over at least. I'll see if that translates to having an incomplete skull.

The foam appears to be setting up rather firmly. I'm wondering a bit about the whole 'wait 3-7 days' thing on the how-to. At this rate, the skulls will be fairly solid in 24 hours. But maybe you have to wait the extra time in order for them to super harden...? I'm new to the expandable foam medium, so some trial and error is in order. In the meantime, I'm eager to see how the first batch of skulls turn out. Also in the interim, I'm doing more of the crochet eyeballs...cause they're kinda awesome, and suddenly wanting a whole rainbow of different eye colors.