~17 yrs ago I mentioned here making a giant slinky by taping together about sixty 13" Aerobies on alternate edges. Regrettably, I can't find my videos, either digital or analog. The best featured it descending the roof of the Cherry Chase School and then stepping all the way to the ground near some unimpressed kids playing basketball. It was also able to go a few steps down a particularly steep section of a street near my house. The device exhibited some "momentum" by sometimes going an extra step after reaching a level surface. Anyway, I think a neat engineering class challenge would be to design the slinky needing the least inclination. Helpful might be if the last few coils on either end were heavier and stiffer: those on the upper end lying not quite flat, and those on the lower end releasing stored energy near the end of each step. --rwg