Gears are steampunk icons.
I didn't have much of an idea how to create this, so I asked for help from various classmates and the teacher.
I started with a flat extrude, the placed a hole on the bottom layer and extruded it upwards, creating a ring about .5cm wide, and did the same for the center axle, placing it on a separate sketch. I drew one half of an arm branching from the center axle, then drew a mirror line to reflect it so it was even. Afterwards, I added five arms in total.
The design for the teeth were supposed to be radically different; I was going to make them tall and rounded, but my teacher told me to try sketching them a different, more practical way, which formed the finished project.
After toying around with making sure the arm extrusions would form to the axle, I had to tackle the problem of how to make multiple teeth; the process I used the first time wasn't working, and instead made almost pizza-like slices across the plane instead of tiny teeth. Then I realized that I had to close off the structure with an arc and it worked after.
I added the fillet center axle as a last minute decision and, overall, I like how it came out. The whole thing is 3in in diameter.