Saw one of the sheets of plywood in half lengthwise, leaving a pair of 2-by-8-foot pieces. Saw a 2-foot length off a pair of the 2x4 boards. Saw a 3-foot length off another pair of the 2x4 boards. You should now have one large piece of plywood, two smaller pieces of plywood, six 8-foot-long 2x4s, two 6-foot-long 2x4s, two 5-foot-long 2x4s, two 3-foot-long 2x4s and two 2-foot-long 2x4s.
Build a rectangular frame 6-feet tall by 8-feet wide out of the 2x4s. Once the frame is complete, add an 8-foot-long crosspiece to the frame 2 feet from one end. Mount one of the 2-by-8-foot pieces of plywood to the bottom of the frame. Nail it to the crosspiece, bottom and side boards. This will form part of the front of the stage.
Build a second rectangular frame that is 5-feet tall by 8-feet wide using 2x4s. Add an 8-foot-long crosspiece 2 feet from one end of the frame. Mount one of the 2-by-8-foot pieces of plywood to the crosspiece so that it can be nailed to the frame on all four side. This will form the back of the stage with a firm surface to mount scenery.
Position the frames so that the plywood pieces face forward on both frames. The 6-foot-tall frame will serve as the front of the stage and the 5-foot-tall frame will serve as the back of the stage. Also position the frames so that the plywood piece on the front frame is at the bottom of the frame and the plywood piece on the back frame is at the top.
Connect the bottoms of the frames at the corners with the 2-foot pieces of 2x4s. Connect the tops of the frames at the corners with the 3-feet-long pieces of 2x4s. There will be excess 2x4 at the top connection. You can saw it off. The frames should now be able to stand up.
Draw a rectangle 3-feet wide by 2-feet tall on the remaining 4-by-8-foot piece of plywood; center the rectangle on the 8-foot-long side, 1 foot in from the side. Measure 15 inches from the ends of the rectangle toward the ends of the plywood. Use these marks as a center point to draw a pair of 18-inch circles flanking the rectangle. Thus, along an 8-foot-long side, you should have 6 inches of wood, an 18-inch-diameter circle, 6 inches of wood, a 3-by-2-foot rectangle, 6 inches of wood, a second 18-inch-diameter circle and 6 inches of wood.
Saw out the rectangular and circular spaces. These openings will serve as the stages for the puppet shows.
Mount the plywood that has the stage openings to the front frame. It should fit in the space above the plywood already attached to the bottom of the front frame. Make sure the stage openings are at the top of the frame. You should be able to see the piece of plywood mounted on the back frame through the stage openings.
Smooth all the rough edges with sandpaper.
Prime the front of the stage. When it dries, paint a design of your choosing on the front of the stage. Paint the piece of plywood mounted on the back frame white so that it doesn't distract from the stage.
Cover the gap between the front and the back frames with fabric. The top piece of fabric should be mounted to the frame on all sides. The side pieces of fabric should be attached only at the top to allow access to the stage.