First off, congrats on such a wonderfully fun child, I hope my kids share at least one of my interests.
Secondly, the humidity does in fact impair anything drying, living in KY, its one thing I've learned.
Three, if you have a length of copper wire and a couple D cell batteries, I recommend you(and not the child) make a foam cutter for super smooth cuts.
Not sure if it will work on the coolers, but I've had great luck with it on insulation,
Can't wait to see more.