My rulers have a dip in the centre, so perfect to fill with things.
I've used black glitter card on one, like the one I bought, and the others are made with loose glitter...very messy, but so cool.
In the video I didn't but I made more and I used painters tape to protect the rulers outside the dip...not sure why I didn't think of it from the start, except that I thought I would be more precise.
For my glue I used Creapodge ( a kind of Modge podge) and Glossy Accents. I prefer the Glossy accents to the Creapodge, but you might have better glues. I don't think Multi Medium Matte is a good idea if you want shiny glitter, cos it will matte them down.