The wearable LEDs guide reduces a lit costume's evening to one division: hours = mAh ÷ mA-draw. What makes the division work is knowing the two numbers on either side of it, what the strip drinks per meter, and what the bank holds in honest hours.
The guide's table carries three types and their draws per meter: a single-color strip pulls about 0.4 A, the cheap, long-runtime choice when one hue carries the scene; analog RGB about 0.6 A, whole-strip color changes, simplest wiring; addressable (NeoPixel) about 1 A at white, per-pixel patterns, gradients and motion, at the top of the thirst. Multiply the draw by your meters, compare it to the bank in mAh, and the evening's math is done.
A 10,000 mAh bank on a 1 A build runs about 7 hours with the inefficiency margin already paid, "honest hours" being the guide's term for the gap between the mAh printed on the packaging and the mAh that shows up at work. From there the guide's planning rule carries the build to the doors: set the daily presets at 30–50% of full draw (the guide's callout puts it plainly, full white is a display mode for photos) and double the hours you computed. The doubled figure is the plan that survives a long con day, and the LED battery cheat sheet on the build sheets page prints the same table for the bench.
Three habit-rows from the same guide finish the plan. Inject power every 2 m of strip, the far end stays bright instead of dimming through the voltage drop. Put strain relief on the joints (hot glue on the wire at the entry), con floors kill loose connections first. And put a quick-disconnect at the battery so charging never requires un-building the costume. A translucent channel, 8–10 mm of something between LED and eye, finishes the light into a line instead of a dotted string.
Hang the mask. — the workshop crew