Fairly trivially done in any Indigo Asteroid level, but levels 2 and 4 of the first zone are the easiest place to get it. Simply grab the indigo asteroid power-up, transform, suck in enough material to go through the wormhole at the center of the loop, and then gather rings inside while waiting for 20 seconds to elapse. Don't collect all the rings inside the alternate area until the achievement pops.