Consider rolling more balls than you'll need, just in case.
This will act as the yoke of the light. Make the gap large enough to fit the cord through but small enough that it won't slip.
You might need to cut some of the skewers short to fit into the design. Make sure the frame is sturdy.
Consider matching the color to the color of the light socket.
This project has a 4" base and 4.5" sides, but you can choose your own measurements and shapes.
Slice through the top layer of your cardboard pieces on the angle lines so that you can bend the shape as needed.
Tape the cardboard pieces together while making sure there are no cracks or creases.
Pour the cement so that it is about 1/3" thick.
Wait for the cement to set a bit and then turn your shape on it's side so you can pour more cement into the mold.
Cut the cardboard away from the cement and remove it and all tape that is attached.
If there are any chunks missing or strange spots - mix up a bit more cement, patch them up and then sand them.
For 3 pockets you will need 9 separate triangles that you will later glue together.
Make sure that for each pocket there is one side whose length matches the sides of the center triangle.
Attach the appropriate triangles for each pocket with masking tape, making sure the appropriate sides match.
Glue each of the triangles for the top of the pocket, as well as the sides of the triangles to the back piece.
Cut triangle frames from the plywood and and glue on the pre-assembled wall pocket fronts.
If you don't wish to keep your wall pockets raw wood you canpaint them inside and out, since both will be seen.
Plywood is thin so make sure to hammer the picture hangers within the outer frame so that they don't poke through.