Prototyping

Our very first 3D-printed attachment exposed all of the improvements we needed to make. As it was also the first time any of our group members had 3D-printed an object, we were not yet aware of if our design would be sturdy enough. However, it was evident how thin and fragile we made it when we took it off the printer and one of the massage balls immediately detached. So, we noted to make the arms thicker and directly attach the massage balls to the longer arms for a more secure bond.

We made the modifications, but the arms were still not strong enough to hold the massage balls as it rotated on the motor. So, we increased the width of the arms even more. 

Now that the arms had the optimal diameter, we thought that the sleeve would be too bulky if we had the motor positioned on top of the massage balls despite using a shorter motor (as shown in the picture below). To resolve this, we flipped the massage balls so they were facing down and added extra supports and arms. 

We were very close to calling this our final design, but when we tested it, the massage balls would get caught on the wires as it spins. Another concern we had was if the motor would heat up and irritate the skin since it would be in close contact. Also, we did not address this problem previously, but in all of the designs, the system would stop rotating as soon as it makes contact with something. We believed that this was due to the massage balls merely being partially filled with filament which did not provide any weight to them. So, we decided to use small, steel marbles as the massage balls. To attach them, we replaced the balls on the 3D model with hollow hemispheres for the steel marbles to fit inside.