Building a lap guitar

Have any of you ever built a lap guitar? I've had someone ask me to make one for them, but never have. I was just wondering if any of you fellow luthiers were familiar with them. This guy said it's called a "steel lap guitar," but can be made from wood. They look fairly simple, but then I've never seen one "in person." Anybody got anything they can tell me about them, or could tell me where I could get the supplies & instructions for making one?