Bouncy castles are usually made from a thick polyvinyl chloride plastic which is commonly used to coat electric wires. The plastic is cut and sewn into a bouncy castle before an electric blower is attached to inflate it. Cheaper inflatable castles can be made at home from polyester and an airbed pump. The polyester bouncy castles do not last long, but can work well for home use. An inflatable moonwalk is one common example of a bouncy castle.
Cut a 3 m (10 foot) long by five foot wide piece of polyester. Fold into the shape of a tube and stitch tightly into the shape of a pipe, leaving both ends open. Repeat until you have four columns.
Insert the four columns into the cardboard box, one column for each corner of the box.
Cover the cardboard box and part of the columns with the remaining polyester fabric and sew the ends tightly closed so that everything is sealed.
Cut a very small hole in the bottom of the polyester fabric and the cardboard box to attach the air pump. Seal around the pump with hot glue.
Seal around the polyester column edges with hot glue, covering all stitching.
Turn the air pump on and let the bouncy castle inflate. Keep pump running while the castle is in use.
Adding several layers of polyester will make the bouncy castle more durable. Keep the air pump on so the bouncy castle does not deflate.
Use caution when working with needle and thread. A polyester bouncy castle can be used in the home only and is not for rental purposes.