Step 1: Parts
I had to start somewhere--the wheels. I went to my local hardware and purchased two vacuum belts. I wanted these for traction--and they determined the ultimate diameter of my wheels. The shaft on my 40 rpm gear motors determined what size the hub needed to be.
Here's the major parts:
Arduino Motor Shield
Gear motors (12 volt, 40 rpm) Jameco #253518
Tail motor Jameco #2128219
Smile solenoid Jameco #149762
DPDT 5 volt relay Jameco #139977
Two 1K resistors
Three 9 volt batteries and battery snaps
Seven AA batteries and holders
Heat Shrinkable Tubing
Body--For printable part list:
He evolved as the design process started.
For every body piece, I needed dimensions before I could design the part in software. Even if the part is made from plywood and bottle caps, knowing the critical sizes and placement of objects is important.
This is the base--could be plywood or plexiglass. Actually, this is a good starting point for design using 3d software--just a flat piece with rectangular cutouts.
The side panels get more tricky--they need to fit the bottom piece and support the motor.
Screw the motor to the side panel.
Solder wires to the motor while it is easy to do so.
Print the front piece--with the bow tie raised.
Snap the side pieces onto the bottom piece and the bow tie onto the front. Push the wheels onto the shafts. Add a set screw into the wheel collar.
Paint the bow tie (my wife took care of this).