I made myself a rack out of some plywood and scrap wood. It's basically two square pieces of plywood separated by a column of wood in the middle (so it looks like a barbell if it were on it's side). Then I put posts on each corner, and ran a strip of wood from each corner to the next to keep the rods in. So, you basically stick the butt of the rod in the gap between the cross strip (the one running from corner to corner) and the top plywood square, and then put the rod vertical in the rack. The base kind of acts like a stopper to keep the butt from sliding inwards, and the cross piece keeps it from going outwards, and the top plywood piece balances everything out. It's just like if you had a pencil in your fingers, so that your index finger was below, middle finger on top, and ring finger below. Same exact principle.
-Brian