Are you ready for all three chords together? Here we go with G major, C major and D major. Definitely use scaffolding for this one; you´ll want to use G as your first chord to sound, and, at the very beginning, you may also want to use D as your last chord to sound (as indicated in the screenshot).
With three chords, you may need to use a little scaffolding whenever you increase your metronome speed in Musical Gym.