You forgot to add in your instructable how to cap the bottom. Wasnt quite sure what you used in the picture, but I took a 3" threaded cap and placed it upside down in the tube. This way it still sat flat and a little less dirt is needed. When i glued the cap in place I spun it as the glue dried this ensured a leak free seal. One could also use caulk as well once the cap is in.