Mixed my epoxy. Then covered the balloon in epoxy-soaked twine.
I sprayed the balloon with mold release, hoping that would be enough to remove it when done. I started off with the basic 2:1 pumps of epoxy, stuck some twine in the cup, then wrapped it around the balloon. Dunking twine in the cup while making sure the balloon stayed in place was a bit hard to do as I was doing this by myself. Eventually my method changed to just grabbing a glob of epoxy and smoothing it over the next section of twine as I wrapped it around the balloon. I just mixed more epoxy as needed.
Hanging out.
The entire balloon was pretty epoxy-fied and sticky, so hanging seemed like the best option once done. The time to become dry to touch was 4 hours, and full cure time was 7 days. I set it here for a day, then tooke it down to pop, as I didn't want the balloon sticking to the twine too much.
Pop?
The balloon ended up sticking to the twine despite my attempt with mold release. I poked a hole in it...and watched as nothing really happened. I then went about removing all of the balloon pieces stuck by poking holes everywhere and pulling out pieces I could.
Taking out pieces.
After poking more holes, I pulled pieces out by hand, then by tweezers. This took roughly half an hour, which wasn't too bad. There are still a couple really small pieces of balloon left inside, but you can't see them from the outside.
Cut a hole, test out a light.
I cut out a small hole at the base of the structure, and stuck a bulb inside to test out what it would look like as a lamp. I might try wrapping extra twine around it all; it feels like there's a bit too much empty space right now. I'm also curious about trying the same process, but with yarn, or some string smoother than twine, and having a more methodical design (stripes, cross hatch).