That's pretty much a perfect description 😁

Basically, you put the camera on a tripod. Put into bulb mode and set off the exposure. Then wave anything that lights up in front of the camera. As long as you don't get between the camera and the light and you don't shine too much light on yourself, you won't show up in shot.

The tricky bit is drawing in the dark as you can't see what you've already done, so it ends up being about muscle memory and good spatial awareness