Instructables user Bctcteacher writes:

My students love to build things and throw stuff so let’s put both together! Now, for the green part. Let’s see if we can make something that is recyclable and fun! Looking around the classroom, I see lots of cardboard (used shipping boxes) and a good supply of Elmer’s glue. So, with a little help from Autodesk’s CAD program Inventor, I whipped up a nice little Catapult (Hence “CAD-A-Pult“).

Becky Stern

Becky Stern

Becky Stern ( is a DIY guru and director of wearable electronics at Adafruit. She publishes a new project video every week and hosts a live show on YouTube. Formerly Becky was Senior Video Producer for MAKE. Becky lives in Brooklyn, NY and belongs to art groups Free Art & Technology (“release early, often, and with rap music”) and Madagascar Institute (“fear is never boring”).

  • hurf durf

    Stop calling everything “green.” Its seriously getting annoying.

    There’s nothing green about this. It used materials already raped from the earth (neutral, not green), elmers glue (not green) and electricity (way not green).

    Want to be green? Turn out the lights and sit in the dark. Or go outside and decompose. Hurf.

    • jammi

      To quote you, “It used materials already raped from the earth…”. It seems to make sense that any garbage that’s not in a landfill is already, technically, green.

      I can’t see how a catapult could be the Saviour of the world, but I do see someone brighter than me figuring it out.

    • BctcTeacher

      Wow what a comment Hurf. Note the first part of the project was to do some recycling and have fun. Repurposing already used cardboard, as an object lesson leading to better design. Note everything we used will break down ( even the tape).
      So Hurf turn off your computer, stop raping the earth by using fossil fuels to spout crap and take your own advice and “go outside and decompose.”