Given the high volume of material being processed at Allen's Pond, we decided on twin bay design, with a hinged top and a sliding front for each bay.
The frame: Assemble the frame with three 5' 10" x 2" x 3"s (joists) and two 33" x 2" x 3"s (headers). Mark the center of each header. Arrange the boards into a rectangle, with the joists parallel to one another, butting up against each header, two flush with the ends of the headers and one running between the middle of each header. Nail the headers to each joist using 3" 16d framing nails.
The posts: Next cut six 33" x 2" x 3"s. Cut a 1" x 1" notch at the top of the six posts. Mark the center of each joist. Set the posts perpendicular to the floor, with the notches facing inside the bin. Bolt the front posts to the inside of the front joist, the rear posts to the outside of the back joists. To bolt: Drill two 1/4" holes for each post through both joists. Hold the posts in place by hand, marking each with a pencil through the drill holes. Drill the corresponding holes and join each post with two 4 1/2" carriage bolts, running from the outside of the joists to the inside of the frame. Secure with nuts and tighten against each post.
The floor: Cut eighteen 34" x 1" x 4"s for the floorboards, notching around the posts and allowing for a 1" overhang beyond the back of the rear posts. Beginning flush with the left side, nail the boards to the frame with a 1/8" gap between each.