I decided on using a rotary encoder with a pushbutton integrated into it as the only source of control for the clock, to switch between the different modes (12 hour, 24 hour, date, temperature, day of the week, setting time, etc.) and I needed to machine a knob to fit the encoder since it didn't come with one. I used the machine shop on campus to lathe a small ~15 mm knob out of brass, with a brass plate that would hold the knob and power plug to the side of the case.