Every now and then I'll get someone asking me about which ruler I use in my videos. It's this Wescott grid ruler that I picked up ages ago. While having a transparent grid is useful for figuring out spacing and perpendicularity, it ultimately not something that you can't achieve with any old ruler (or a piece of paper you've folded into a hard edge). Might require a little more attention, a little more focus, but you don't need a fancy tool for this.

But hey, if you want one, who am I to stop you?