By Samuel Johnson and AnnMarie Thomas
Making play-dough creatures is fun, but making
them with light-up eyes and moving parts is even
more enjoyable. We thought it would be better still if
we could make the circuitry out of the dough itself!
Most play dough is already conductive, but we
needed a way to insulate the conductive dough. We
came up with a sugar-based dough that works well
as an insulator. It’s pliable and resistant to blending
with the conductive dough.
Rainy day and fidgety kids? Whip up both types of
dough, gather some LEDs and batteries, and create
your own menagerie of squishy circuit creations.
Add a motor or two for sculptures with moving parts.
Feeling adventurous? Play with the salt content of
the recipes to vary their conductivity.
1. Make the conductive dough.
Reserve ½c flour, and mix the remaining ingredients
in a medium-sized pot. Cook over medium heat,
stirring continuously. The mixture will begin to boil
and get chunky. Keep stirring until a ball forms in the
center of the pot. Once a ball forms, turn off the heat
and remove the dough to a lightly floured surface.
CAUTION: The dough will be very hot!
Flatten it and let it cool for a couple of minutes
Slowly knead the remaining flour into the ball until
you’ve reached the desired consistency.
Store dough in an airtight container or plastic
bag. In the bag, water from the dough will create
condensation. This is normal. Just knead the dough
after removing it from the bag, and it will be as good
as new. Stored properly, it should keep for several
weeks. If it dries out, just add a little more deionized
water and knead it with some flour.
2. Make the insulating dough.
Mix the dry ingredients and oil in a pot or large bowl.
Mix in 1Tbsp of deionized water and knead; repeat
until the mixture becomes moist and dough-like.
Remove the mixture from the pot or bowl, and
slowly knead flour into it until it attains a firm consistency. You should use almost the entire ½c of flour.
NOTE: You probably won’t need more than ¼c of
deionized water, but have ½c ready just in case.
78 Make: Volume
YOU WILL NEED
For conductive dough:
3Tbsp cream of tartar
1Tbsp vegetable oil
Food coloring (optional)
For insulating dough:
3Tbsp vegetable oil
1tsp granulated alum
½c distilled or deionized water (check lab
4 AA batteries in a battery holder
Low-current DC motors
Samuel Johnson is from Blaine, Minn., and is an engineering
student at the University of St. Thomas. AnnMarie Thomas is
an engineering professor at the same university, and co-director
of the Center for Pre-Collegiate Engineering Education.
Illustration by Julian Honoré/ p4rse.com; photograph by Samuel Johnson
3. Make squishy circuits.
Insert the 2 leads from the battery pack into 2
pieces of conductive dough, separated by a lump of
insulating dough (we recommend using food coloring to differentiate the doughs).
Insert an LED so its anode (long lead) is in the
positive battery lump, and its cathode (short lead)
is in the negative battery lump. It will light up!