PVC Frame Fort
If you like the simplicity and ease of constructing forts using a kit, make your own frame using simple and affordable materials like PVC piping. Parents can cut the PVC to the desired length, and then kids can help join the pipes together to form a simple playhouse. The best part of this type of fort design is the wide selection of sizes and shapes the kids can design – the shape your fort takes is truly limited only by their imagination. Use scrap fabric or old sheets and blankets to cover your DIY frame and complete your fort.
Don't want to spend money on piping? Roll old newspapers to make your own fort frame [source: Waken]. It works similar to PVC, but costs nothing, and serves as an excellent way to recycle household materials instead of throwing them away. Encourage your kids to use plenty of layers of paper to ensure the structure is sturdy and durable.