I created the rain barrel out of a 4 ft section of 8 inch PVC pipe I got from a local contractor. I used an end cap and sealed it with 5200 marine adhesive. Then I installed 2 3/8" MIP hose barbs and coated the joint with more 5200. The one on the top is the inlet and the one at the bottom is the outlet. The inlet was installed as high as possible based on the gutter collection point.
I also installed a chain to keep the barrel from falling over when full.
NOTE: Use the fast curing 5200 marine adhesive. The normal stuff takes a full week to cure and waiting gets really old!