Square box around 18″x18″my son is 10 and that is the size we used
Construction paper
Rubber cement
Black spray paint
Black duct tape
X-Acto knife
Instructions
Spray paint the sides and top flaps of the box.
Cut off bottom flaps.
Measure and cut out 45 – 5 inch x 5 inch colored squares from construction paper, 9 each of 5 different colors.
Use black duct tape to secure the sides of the top flaps.
Cut a hole using the X-Acto knife big enough for their head to fit through in the very center of the top. You will have to go through 2 layers because of the flaps. I did one layer at a time. I then used more duct tape to make sure the flaps were secure and around the opening to avoid neck irritation from the cardboard.
Cut a 4 inch diameter hole on each side, 2 inches from the top and centered for the arms.
Apply rubber cement to each square (and to the box for a better bond) and place evenly along each side. You can shuffle the colors up for an unsolved cube, or do a full color on each side for a solved cube.
Allow to dry.
If using Modge Podge, apply to all surfaces and allow to dry.