Also, many people, including myself, use a cheap rubbermaid container for their sump. I found the perfect size container at Target for like seven dollars.
I chose this route because I had tried various glass aquariums before and always had the problems of it being too tall and was a pia to get the skimmer in and out, or not fitting underneath the stand. The rubbermaid container was a lot faster to implement and much cheaper to buy than building a sump from scratch out of glass or acrylic. Plus when the doors to the stand are closed you can't tell anyways.
