Really remarkable 2D/3D sketching interface from 1999:

I was in the audience at Siggraph when he did the demo. He got the loudest clap at the end; and another one when somebody asked a question about how it worked and he explained it by drawing sketches digitally (quite novel at the time). His whole approach was visual; very inspiring.

My friend Andy Nealen worked on a follow up to Teddy during his PHD ()