Phone, mount, storage. The 60-second equipment check before you leave the shop.
Anything in the last four years works. iPhone 12 or newer, Pixel 6 or newer, Samsung S21 or newer. Shoot at 1080p, 30fps. 4K eats storage and uploads slower for no extra trust.
A magnetic chest mount or a small gimbal helps for stages where both hands are busy — soldering, cutting, sanding. Not required. For most stages, prop the phone on a level surface or hand it to your apprentice.
A full day of stage clips runs 3–6 GB. Keep 20 GB free on your phone, or upload between stages so the day's footage moves off your device as you go. The Estia app will warn you if you're running tight.