Quick n' Dirty Doodlebot

Last week during a visit to the local science museum (OMSI), my middle daughter and I built a "doodlebot" out of a little stepper motor, a battery, a hunk of Styrofoam, and a few other things. My son had one of his idiosyncratic attacks of stranger worry and didn't do the project with us, but Grace and I had so much fun that I filed the project away as something to try at home. I immediately found plans for a "DoodleBot360" on Instructables, but as per usual I wanted to make it even simpler.

At its simplest, these "bots" consist of a platform that holds a pen just barely in contact with the surface, propelled by some sort of motor. So you should definitely use your imagination to come up with different recycleables to use as the platform and legs. For instance, I thought about using the legs from our "Cooties" game, and at OMSI they used toothpicks. Cardboard would be fine as a platform although it probably won't have as much holding power on the legs: you may have to glue or use sticky-tac to keep them in place.

My 4 year old and my 6 year old built 3-4 different models in about 30 minutes using these materials

Both models

• Narrow Crayola markers

Style 1 (Similar to Instructables DoodleBot360) 

• A motorized toothbrush from the Dollar Tree
• A plastic lid from a large tub of yogurt
• A hole punch
• Electrical tape

Style 2 (Similar to OMSI's doodlebot) 

• A milk frother from Ikea (under $3 and used daily for my morning coffee!) 
• A section of a green floral brick from the Dollar Tree
• A rubber band
• Several golf T's 

Instructions for Style 1

• Mark three roughly equidistant spots around the edge of the yogurt lid, and use the hole punch to punch through. 
• Take the caps off three markers and insert them into the holes.
  By pure luck, our standard hole punch made holes just exactly the size of our markers, and the ridge on the marker where the lid stops was enough to keep them in place. I was prepared to use sticky-tac to hold them steady otherwise. 
• Lay the motorized toothbrush across the lid and attach it with a piece of tape

Instructions for Style 2

• Cut a green floral brick into quarters (length and width-wise) using a bread knife
• Insert 4 (or more) gold tees near the corners of the brick. I placed mine so the bot would stand on the wide part of the tees; Grace chose to put hers all the way through so the bot stood on the points. Both methods worked fine. 
• Somewhere in the vague center of the brick, shove one or more pens into a hole started with a golf tee.  Carefully push through just to the point where the tips touch the surface. 
• Lay the coffee frother across the brick and hold in place with a rubber band or two. 

To play, get a large piece of paper or cardboard (we used the cardboard circles from our pizza last night!) and carefully turn on the motor while holding the 'bot above the surface. Place 'bot in the center of the drawing area and let it go. Make any minor adjustments necessary to keep the pen in contact with the paper, and be ready to catch the 'bot before it runs off the drawing area. 

Results

When used with the toothbrush motor, both styles of 'bot generally wanted to move in a circle. The coffee frother had a considerably larger oscillation - one of the two we used was actually bent, which made for a Very wild motion. Bots using this motor tended to draw dots over a large area of the paper, and it was challenging to keep the pen in contact with the surface.

The circular 'bot was the most stable and drew the most regular shapes. 

The foam brick bots were probably more fun, though, and certainly allowed for more steps to be performed by the kids.