Circuit:

1. Secure two 12 inch wires to ends of green LED with electrical tape
2. Assemble circuit as detailed in Appendix B.

Mechanical Assembly

1. Cut a 4 inch radius half circle out of cardstock.
1. Print out the insults, as shown in Fig. 1, and glue to the front of the shape.
2. Align servo blades with bottom straight edge and glue to the back of the shape.
2. Cut the back and top off of a standard size cereal box.
1. Paint the box gray.
2. Cut a hole in the bottom side, to become the front, the same size as a toilet paper tube.
3. Cut a slot in the front side, to become the top, which will fit the wires.
4. Cut two slots to fit the motor mount.
3. Paint a toilet paper tube gray.
1. Cut one end diagonally at a 30 degree angle to create the angle shown in Fig. 3.
2. Secure the diagonal end with electrical tape, holding the barometric pressure sensor in place at the bottom of the tube and allowing the wires to pass through.
4. Cut holes in a sheet of cardstock as shown in Fig. 4.
1. Paint the sheet gray.
5. Cut a second sheet of cardstock, to become the motor mount, as shown in Fig. 5.
1. The central hole should fit the servo motor.
6. Use the discarded cereal box side to create a small, open bottom, stand for the button with dimensions 0.85” x 0.85” x 0.2”.
1. Cover with electrical tape.
2. Create small holes to pass the button legs through the tape and cardboard.
3. Connect wires below.
7. Glue the front sheet of cardstock to the front side of the box, aligning the holes for the tube.
8. Place all circuitry inside.
1. Pass LED through the slot at the top of the box.
2. Connect the servo wires to the breadboard and Arduino through the same slot.
3. Insert the tube through the holes and connect the pressure sensor wires.
4. Pass the button assembly underneath the cereal box and position it to the right of the device as viewed from the front.
9. Insert the LED into the hole in the front panel and secure it with electrical tape.
10. Press fit the motor mount onto the back of the servo motor and insert its legs into the slots at the top of the box.
11. Ensure the “Go on, try me!” text is centered in the display window.

Given a chance at a do-over, I would have purchased fewer parts. I purchased two different kinds of pressure sensors and two different buttons, assuming that one would be a better fit than the other, and I was correct. Now knowing which ones work, I would only purchase what I would use. I also would have used a paper towel tube as opposed to a toilet paper roll, so that the user would not have to crouch as low to use it.

Given an additional $20 and another month, I would have both invested in a higher-quality barometric pressure sensor and utilized laser cutting. The current sensor does the trick, but only reads integer values of hPa, and its reaction time is delayed by upwards of two seconds. A more expensive sensor may be capable of reacting faster, eliminating the need for the 5 second delay in the code. Using laser cut wood instead of cardboard is mainly for aesthetic purposes, but it would also have made the structure more stable. The motor mount in particular is questionable in its stability and is unlikely to hold up given an aggressive customer.

When the device is assembled, use it to trick your friends and remind yourself and others of the consequences of poor dental hygiene. Turn on the battery pack. Instruct the soon-to-be victim to press the button, then wait no more than 5 seconds before blowing hard into the tube. Ensure that the victim reads the insult displayed in the window and takes it to heart.