The Brooding Hen (photo from their site).
The instructions are easy to follow and if you live in a tool-filled home like I do, this will be pretty inexpensive to make! I'm excited to construct this for my littlest one...she's showing more and more interest in showers lately in an effort to keep up with her big brother and sister. Hopefully this will keep her in the tub a bit longer. She's only 4 after all!
This would also be fun in the summer attached to a board and brought outside! Just give your children some buckets full of water (including one to catch the water at the end), and a few sticks, boats or plastic Army figures or animals to shoot down the "waterslide."
Check out the list of materials you'll need and the step-by-step instructions at thebroodinghen.blogspot.com.