It dawned on me that I never updated my original post on painting Disney MagicBands. For our most recent trip in August, I followed my original process, but I used varnish instead of clear nail polish to seal the design.
Verdict: While not perfect, the varnish worked much better than the nail polish. By the end of our week-long trip, the adults’ MagicBands were still in good shape whereas the bands belonging to the five-year-old did not fair so well.
Poor BB-8 and R2-D2 ended up a bit battle-worn after a week of Disney. Lil’ Man was constantly taking off his bands and bending the straps which I believe cracked the paint over time. He also constantly bumped his band on objects which scraped the paint off of the R2-D2 band.
If you do choose to paint your MagicBands, then know it probably won’t survive the wear and tear from a little one. Otherwise, using varnish to seal the paint works quite well.