Legos
Cryptography
Marshmallow PVC shooter 
Creation of *mini contraptions from common household items
 * catapults, shooters, launchers, bows...
Sculpey
Kinetic Art Sculptures
Fuzzy Friends (art craft chia pets)
Makey Makey
Little Bits
Snap Circuits
We Do Robots (Legos)
Engineering Competitions (gum drop dome, paper table/chair)
3-D Printing
Ring Cling (test your accuracy and skill and catch the ring on the hook)
Table of Interesting Things (several cool gadgets to tinker with and think about)
Giant Magnifying Glass (Do you want to melt a pile of pennies?)