Ok, yes, a popsicle stick will work for your creasing needs, but this bone folder from Martha Stewart does a better job. Made of sturdy melamine, it can be used for brayering, creasing, and even rub-on applications. I use mine almost every single time I sit down to craft. It feels smooth to the touch and won't bend as you use it (like some cheaper bone folders).
I haven't used this a lot yet but love the feel of it. It is nice and solid and rests well in my hand. I did try it out with the MS scoring board (which comes with a much flimsier version) and really appreciate how nicely this one works. Also, it does fit nicely into the compartment in the top of that tool.
MSC Bone folder is a great help! Easy to use, works perfectly while creasing, marking, smoothing the paper, applying rub-on and many more. It's very handy, solid and indispensable for almost every craft project I start.
Totally recommend it!