They like the idea a lot... can see a tee shirt with a progression of different ways to crack the nut
ice pick / hammer / etc ending with zipper
OR maybe 1 nut 2. sewing machine 3. thread 4. zipper 5. final product #30 then #16
across the top of the shirt? or in a grid?
They also like the way you play with fonts on some of your entries... so maybe that too?