I bought a Flippy Car at a craft fair that would be a good gift item or good item to sell. The flippy car is about 3 inches long, 2 inches wide and about 2 inches tall. The little car runs down a slight incline and when it reaches the bottom it flips over in a somersault and winds up right side up.
Here are the parts needed for the car: I don't think there's any particular magic to the sizes but dimensions close to these would be very good for smaller children --- although I think bigger kids and adults will spend a lot of time playing with it. The flipping action is habit forming.
two PCs 3/4T x 3 x 3 cut into 2 � diameter circle 1 piece 3/8T x 3 x 3 cut into 2 � diameter circle 4 1-inch diameter wheels 4 axle pins available from Woodcraft or Rockler Axle Pins
The 3 circle pieces are face glued together with the thinner piece in the center to give a little style to the car. There's no reason the 3 pieces couldn't be all the same thickness but the 2 plus 1 looks nice especially if the middle piece is a contrasting color such as 2 maple and 1 walnut.
Once the 3 pieces are glued together strike a diameter line across the face of the circle Take the circle to the drill press and use a three-quarter inch or 1-inch Forstner bit to cut out a hole in the center of the circle use the same bit to cut out a quarter-circle from each end of the straight line. These cuts will leave you with two thin tongues on the bottom edge of the car's body. Cut the circles in two. Note: The two pieces will make two cars. Those two tongues will serve as the supports for the axle. Drill a hole into the center of each tongue for the axle pins that will hold the wheels in place. Be sure to position the 4 holes equally so that the car rides smoothly on its 4 wheels.
Here are the parts needed to make the ramp. 1 pc 3/4T x 3W x 8L 1 pc 3/4T x 3W x 3/4L 1 pc 3/4T x 3W x 2 1/2L
Again, dimensions are approximate but the ramp must be wide enough to accommodate the car. The long piece is the ramp itself. One of the other pieces is glued under one end of the ramp piece and the other is glued under the other end resulting in a ramped incline. The taller end can be levelled off if you wish so that it is parallel to the ground. all edges can be rounded over to protect little fingers.
Place the car on the top of the ramp and nudge the car forward. It should speed down the ramp, drop off the end of the ramp and cause the car to somersault. I laugh every time it flips over.