Assemble the pieces by simply screwing them all together. It should fit perfectly if you bought all 1/2" circumferences. So be sure to check everything!
Make two bases. Each base should look like this and include: two flanges, two 1"x1/2" pipe nipple closes, two 2"x1/2" pipe nipple closes, two 1/2" elbows and one 1/2" tee fitting.
I also built that wooden crate and added wheels for extra easily accessible storage!