I'm looking to build my own speaker stands, and I want to avoid screwing up and having to do it over.

My basic idea is two or three layers of MDF sandwiched for the base (12"x12") then taking 4 1"x6" furniture grade boards (birch or maple) and gluing them into a hollow square. This would be filled with Kiln Dried sand, and then topped off with a 9"x9" square of whichever wood I ultimately choose for the sides.
Question 1: am I missing something terribly important?
Question 2: I'd like to include some sort of leveling do-dad, since my floor is a little wonky. I'm thinking of using the type of bolt that you generally find on the bottom of a desk, with a little plastic foot. Should I do something heavier? I own a bench grinder, would grinding the bolts to a point be good, or a waste of time?
OK, so question 2 turned into more than one question.
Oh, and one more question - is Liquid Nails an adequate glue, or should I be using Green Glue or the like?
Thanks
MPEDrummer