You'll work better with a slave-flash, but also a cable connected one is good. Then you need a diffuser to make the light reach all 360° around you. You can build it yourself, ops you have to built yourself, because I think it doesn't exist! ...if it doesn't exist it shouldn't be so useful, you say... right, or maybe I'm a genius! ;-)
Anyway, this is what Instructables is intended to, let's build it!
Step 1: The glittering container
Sorry if I post some images you've already found on the other tutorial... I could have posted all in one, but I though it also could became annoying.
Step 2: Let's heat it
Step 3: And fit it
Once your container is soft you could try to fit it onto your flash, then wait it gets solid, take it away and remove the tape to check it fits with the right tension. It's better it's a little loose because my plastic tends a little to recover original form.