This is the most fun I've ever gotten out of a levelsketch!
The ones at the bottom really had me wondering for a bit there, but
(press the quote button to read the size 0 text)
[size=0]I eventually realized that you don't need the rocks in the top center to crack the nut there, but can use the ones in the entrance on it. That freed me to use two rocks on each side of the bottom.[/size]