I've been thinking about some designs, too... I have a center console, and I like it, but it can be tricky to find spots for horizontal rod storage. I'm thinking about like the driftmaster tip savers, but using an L-bracket instead of a T. They need to be easy to take on and off, and I want to make it where they will flip around so they hang inside the boat on the highway and during launching/loading, but once I'm on the water, I can turn them around so the holders aren't protruding into the boat area at all....
I was thinking about using 1" square aluminum tube and TeamHookSetter had the idea of using something like this on the horizontal part of the L-bracket:
Amazon.com : Berkley Rod Rack Twist Lock : Fishing Pliers And Tools : Sports & Outdoors