As of 2016, you can find directions for building a simple pottery kiln at Homeschooling-Ideas.com. The directions call for using an old oil or metal drum, refractory cement, a ceramic fiber blanket, a soldering burner and a kiln shelf, and the kiln receives power from a glass bottle of propane.
You can also learn how to build a basic ceramic kiln by visiting Skutt.com. The website includes diagrams and variations for kilns of different temperatures and materials.
If you wish to create a solar kiln, SolarKilnInfo.com also posts solar kiln instructions from several reputable sources, including Virginia Tech, the University of Wisconsin and the United States Department of Agriculture.