More details available at http://www.creatrope.com/blog/make/diy-indoor-playhouse/
Step 1: Find a Good Spot for the Playhouse.
Step 2: Cut and Install Materials, Ladders and Slide
Step 3: Cut and Install Materials, Ladders and Slide
Note: The safe building, engineering and use of the following project is entirely your responsibility. The description is how I built it and may not be appropriate for your home layout or intended audience. The guidelines for use and parental supervision are identical to what they would be on a backyard or outdoor playground. It is not inherently safer just because it is indoors.