The tools used — the material was screwed into place throughout the process rather than using clamps:

The material: 2′ x 4′ x 1/2″ MDF via Home Depot:

First guides (I thought I might need to make a second one):

Cut circular portion:

Drawing guides for straight side, 3.125″ from the outside edge of the path to where the jig guide will go:

Screwed jig into place to guide border cut:

First border cut, jig moved for second border:

Jig screwed into place for final inner cut. At this point I realized I should have done this cut before cutting out the borders, so that I could have screwed the jig to the material outside the piece’s borders rather than having to drill a few more holes into my piece:

This edge didn’t come out too well — I think I should have been more careful to align the router’s starting position, and also ended up cutting too far off the other side before stopping:

Finished, sanded piece:

In retrospect, the three resulting screw holes could have all been avoided by using the unused portions of the board instead.