This summer, PBS Kids challenged kids aged 5-19 to spend their summer vacation recycling, reusing, and re-engineering everyday materials to create the next great green invention as part of their Trash to Treasure competition.

After combing through hundreds of entries, the judges were able to narrow the field down to three Grand-Prize winners, two of whom happened to be sisters. Lilly, 12, and MaryAnn, 14, sisters from Ava, New York, and Daniel, 14, from Franklin Lakes, New Jersey each earned a trip to Boston to work with Continuum designers, strategists and engineers, and watch their inventions come to life.

The Trash to Treasure competition is designed to get kids involved in engineering and see how it can make a difference in the world around them. The rules for the contest were simple. The invention had to fit within one of the three categories: move things or people (Mobility), protect the environment (Environmental), or be used for indoor or outdoor play (Play). The invention also needed to be made of at least two repurposed materials (such as fabric, paper, plastic, small electronics, wheels, clamps, springs, batteries, hardware, wood, bike parts, string, rubber bands, cardboard, kitchen gadgets, etc.) Kids were given online tools to sketch out their ideas or upload a photo. (Kids didn’t need to build their invention in order to enter.)

The winning entries—“The Smarter Toilet” (a water saving device); ”Sibling Soaker” (a homemade dunk tank); and “MiBike” (a bike that holds a backpack and protects a kid from rain and snow) designed ways to recycle, reuse and re-engineer everyday materials into new inventions

This is the second Trash to Treasure competition. Last year’s winner, Max Wallack, 13, inventor of the “Home Dome”— a temporary shelter for homeless people and disaster victims — gave this advice to this year’s entrants, “Identify a problem and then try to come up with a solution to it. Be prepared to make several attempts at designing before one design jumps out as the right one.”

Over the weekend, the process of transforming a DIY design to world-class prototype was filmed for a 30-minute episode of a new Design Squad series (to air early 2011).

Check out this video of the kids bringing their ideas to life: