I started working on fixing up the shed for Hydroponics today. Spent over five hours leveling it so far. I was doing some checking a few days ago about what might work good for the plant beds. I am trying to stay away from plywood and boards because of the plastic that will be needed, leaks and all that hub-bub. What I had in mind and still looking (for right price), ABS or plastic pipe about 20 or 24 inches in diameter. I want to cap both ends and saw the pipe in half length wise. You end up with two beds sealed on both ends that need no plastic and will never leak. When the PS gets near, bury them some how until it is over. When the time comes to start "farming" again, there should be no worries about what to use for the beds. So far, ABS pipe is over $8 a foot for 20 inch pipe. I'll get it yet. Working on possibilities of plastic culvert pipe like they put under drive ways. A little over $2 a foot.
Try PVC pipe, very inexpensive and very flexible, easy to cut etc. That's the setup we have for tomatoes, beans, etc. Just make 3/4 of a rectangle (2 feet wide) on each end with a 4 foot long piece of PVC down the middle for support. This will support to 4 foot long deep trays and the corner joints will allow the tilting of the trays to allow for drainage.
Now, how will you cap the end that needs to drain? You need to flood the gravel or sand, then let it drain completely, once or more times a day. This means that the pipes coming out of the drain end need to have a stop in them, attached to the timer also ..
Drain it into a Rubbermaid tub and have a small aquarium pump that pumps it back up through thin pieces of tubing back next to each plants - 4 plants per 4 foot tray, therefore 8 thin pieces coming out of one thick tube. This our setup. The pipes coming out of the drain end just go into a Rubbermaid container; you have a pump in the container; the pump sends the water back up on to the plants through a rubber hose (not garden ... thinner), and even smaller hose goes (thin plastic) goes to each plant ... there are examples in hydroponics books.
I am planning to use PVC fittings and valves on the lower end of the slanted bed.