Fabrication
The parts fabricated for our prototype and final product were primarily produced using either a laser cutter or 3D printer.
Our design consisted of horizontal and vertical base plates, which were placed perpendicular to each other. These plates would be produced from 6mm wooden boards sold by TIW using a laser cutter. After parts have been designed and assembled on the base outlines in SolidWorks to ensure proper spacing and dimensioning, holes are placed and a .dxf drawing is generated. The .dxf drawing is then converted into a .svg and uploaded onto a laser cutter.
We used additive manufacturing for many of the parts in our device due to the technology's ability to supply highly customized parts with difficult to machine dimensions at a reasonably quick pace. This would allow us to not only iterate on designs more quickly, but also to crate multiple versions of a part which could be tested against each other, thus saving time. To produce the 3D printed parts we needed, we would design the parts in SolidWorks. We would then convert the part into an .stl and upload it onto either Bambu Studio or ideaMaker software. On the software, we would select the parts that we wanted to print, selecting various infill, print pattern, and support options, and arrange the parts with optimal spacing and orientation to ensure higher part strength, lower print times, and reduced post-processing. Once the build was ready, it would be sliced and exported as g code. The g code would then be uploaded to the machines and the print would be started. At the conclusion of the print, the parts would be collected and post processed by removing support and sanding rough surfaces. This process would be followed for a wide array of parts throughout or device, which will be discussed in the assembly section.
To adapt materials such as lengths of 8mm and 6mm rail, we used an abrasive saw. With this type of saw, we were able to quickly and precisely cut the hardened steel rods we were using for the slider supporting the follower in our device.
Assembly
The assembly of the final device could be divided into four major sections: The base, the motor and cam, the follower, and the gear train and cylinder.
The base as mentioned previously consisted of two laser cut wooden plates. The horizontal plate had two slots for fitting the vertical plate. For added stability, the plates also have holes for bolting on four 3D printed L-brackets, two per side.
The cam sits on a 6mm rod held up by two 3D printed bearing mounts with raisers containing 6mm ball bearings. This connects to the stepper motor, which is powered by a 
volt power supply and controlled by an arduino and motor driver. The power supply is held above the electronics by an acrylic shelf held off up by offsets.
The follower consists of a slider, which holds the rails, consisting of four 3D printed linear bearing holders offset from the vertical base by raisers. The linear bearing holders hold the provided 8mm linear bearings and space the two 8mm rails. The rails are kept from sliding out of the bearing by 3D printed shaft collars. At the end of the rails are two 3D printed L shaped rail holders that each slot in a rail from the slider, as well as the two 8mm rails that the follower slides along. One of the rail holders is also designed to fit the pen brush, using a slot and 3D printed pen holder piece. Sliding along the two rails are four 8mm linear bearings, 2 per rail, which are held inside of the upper portion of the follower rail holder. The upper rail holder is bolted to the lower follower rail holder, with a sponge-like double-sided tape placed in between to decrease unwanted motion. The lower part of the follower rail holder has the 6 mm rail holding the follower slotted into it and is designed to be rigid to reduce out of plane motion that would resulting in slippage. At the base of the rail is the follower, in contact with the cam, that consists of a wheel, a 3d printed wheel holder, and a metal dowel, which keeps the wheel and holder together.
The final section in the assembly is the gear train and cylinder. This section is attached to the rest of the system by a belt and pulley system, where the pinion for the pulley is attached to the cam rail. A toothed belt connects the pinon to the gear which drives a 6mm rail, which is held up by two bearing holders, bolted to the base, containing 6mm ball bearings. At the end of the rail is a bevel gear. This bevel gear meshes with a second bevel gear on a 6mm verical rod holding the drawing cylinder, which contains magnets that hold the paper. The cylinder is in line with the aforementioned pen holding rail holder. The cylinder rail is connected by a bearing holder and plate, both of which hold a 6mm ID ball bearing and are bolted to the vertical and horizontal base respectively.
Electronics and Circuitry
Our electronics consists of a 12V power source, a stepper motor (17HS4401), a stepper motor driver (DRV8825), two push buttons and an Arduino Uno. The Arduino Uno houses the logic for controlling this circuitry. The two push buttons are for users to control the machine, one for drawing (spinning cam forward) and one for resetting (spinning cam backward).
Figure. Electronics before and after cleanup
Software
The control software programmed on Arduino is based on a state machine. For stepper motor control, we use a popular library, AccelStepper.
