How many of the old school spring steel cycle clips (For your pants/trouser leg) do you think I’d have to laminate together to replace the spring with before it will put a .177 BB through a 2×4?

Learn how to build a catapult the way the ancient Romans did. ... The power behind this catapult’s arm is a spring made from twisted rope. ... New Liquid-Based 3D Printer Takes Minutes, ...

BIRMINGHAM, Alabama -- A catapult, a 3-D virtual reality system for use in training doctors, and a microscope that can magnify an almost invisible object to 200,000 times its size, were among the ...