The above video shows the Sun-Star Deldie Slide Pen Pouch and discusses its attributes more easily than writing a post about it would do. I encourage you to watch the video if you're interested in pencil cases that open from the top and can stand alone like pencil cups.
I purchased this pencil case from Jet Pens. There are other color configurations that might appeal to you so check them out.
Update 7.5.16—Last night as I was heading out to friends for dinner I picked up a light gray Tombow dual tipped marker. I don't use these often. I played with the gray set a couple years ago. I recently bought them again. (Even though they are fugitive I do enjoy working with them for quick sketches.) I'm sad to say Tombows are too tall to fit in this case when the case is fully extended and zipped up.
If you use Tombows this case won't work for you, unless you want to always leave it open. (I always leave it open anyway, as it stands upright in my fanny pack.)