Outcome

Toy helicopter:

Physical principle: wind up, pretend play.

age group: 3-5 years old

interaction:  child uses imagination, winds up toy, pretends it is actual helicopter.

construction/safety: thin sheet metal can be stamped into shape cheaply.  making the helicopter blades will be more expensive, and the wind-up mechanism will have to be geared to not spin the blades too fast, which would be another safety hazard.

what I learned:  something simple often turns out to be more complicated than it seems.

Toy "peek-a-boo"

physical principle: interaction with young child

age group: (people that play "peek-a-boo")

interaction: parent or child winds up toy, which moves arms in front of eyes and makes sound, captivates young child.

construction/safety:  injection molded plastic for the body and arms will be cheap, but the arms could break off  and become a choking hazard.

what I learned:  plastic is cheaper, but less durable than metal.

Toy dragster:

physical principle: motion

age group: 3-6

interaction: child or parent winds up toy, puts on ground.  toy is comically proportioned and brightly colored, moves and makes sound when released.

construction/safety: it could go fast and hit something (or somebody),   small front wheels could break off and become choking hazard.

what I learned:  coming up with original ideas is hard.