Fabrication and Assembly
The linkage mechanism is fabricated out of laser cut 1/8" acrylic and pressfitting bearings into the linkages. We connected the linkages to one another by cutting the 6 mm shafts to size and putting them through the bearings of each linkage. We used 1/8" acrylic as the linkages would have less friction as they crossed one another and the 1/8" acrylic was lighter than the 1/4" acrylic. The base plate was also laser cut out of 1/8" acrylic and had 2 parts as seen in the figures below. 
Electronics and Circuitry
Our system is driven by a 42mm NEMA 17 stepper motor powered by a 24V/2A supply. The motor is controlled by an A4988 stepper driver that is powered by the same 24V supply with a decoupling capacitor to reduce noise in the circuit. To actuate our motor we use a push button connected to GPIO2 of the Arduino Uno that is powered by a 9V battery. The button uses a pulldown resistor to prevent an accidental actuation as a safety precaution. Additionally, the RST (reset) and SLP (sleep) ports on the A4988 stepper driver are connected to each other to create a closed loop because we are not using them. The DIR (direction) pin is connected to port 8 of the Arduino and it controls whether the motor spins clockwise or counter-clockwise. The STEP pin is connected to port 9 of the Arduino and it controls the number of steps the motor takes.
