According to the NIOSA website, large handbags and backpacks won't be allowed on the grounds. In an effort to provide a safer environment as well as expedite entry, bags (even diaper bags) larger than 12" x 12" x 6" and all backpacks are prohibited and will not be held or checked-in at the gates.
Clear bags are encouraged so it's easier and quicker for bags to get screened (attendees and belongings are subject to search). Clear and mesh backpacks will be allowed.
Reminder: weapons are not allowed on the grounds. If caught with a weapon, it will be confiscated and won't be returned.
This year NIOSA runs April 24 to 27 from 5:30 to 10:30 p.m. at La Villita. Advance tickets are $12 while the at-the-gate price is $15.