Theres quite a large US forum I found on these that have some of the old plans online, along with some good and not so good variations on the theme that people have put together.
here
Theres also a local yahoo group that the Brisbane manufacturer runs thats reasonably interesting reading. He also retails parts for the d-i-y brigade, the fibreglass sheeting he sells looks very interesting.
After doing lots of research into construction of teardrops lately, I wandered into a long standing camper manufacturer this morning to have a look at some of their construction techniques - must admit I was a bit taken back, once you look past the glossy paint jobs their very basically built but with 20k+ price tags.