Always Bring More Gaffer Tape
When producing any kind of live show, you use a lot of tape. Masking tape for labelling things, glow tape for marking floors in the dark, surgical tape for positioning headset microphones, electrical tape for wires and cables, and plenty of normal sticky tape, scotch tape, double sided tape for all their normal uses (and plenty of abnormal ones).
One thing that gets used above all is gaffer tape. Lots of it. And not just for the obvious uses of taping down cables and other items. It gets used as a construction material for boxes, containers, and other items. It gets used to secure items for transport, to repair damaged equipment, and sometimes even clothing. If necessary you can even make ropes and cords out of it in an emergency. It's like magic fairy dust for production engineering.
The photo above is a box of two dozen rolls of gaffer tape that I bought about a year and a half ago. Though it may not seem like much, the purchase of that box marked a personal transition from "messing around with a few shows" to "ok, we're taking this shit seriously now." Before the box, we'd always been running out of tape because we were buying it sporadically, roll by roll, whenever we had a show on. But once the box arrived, it was because more shows were going to be happening, and we might as well suck it up and drop a few hundred dollars on the inevitable mountains of tape we'd need.
There's only one significant drawback: the occasional worried looks from house guests who notice the stack of gaffer tape. To the average person without a show business background, a pile of black cloth tape looks less like production equipment and more like the equipment stash of a serial killer.
Patrick Bateman has a lot to answer for.