I use Google Sketchup 7, which you can download free
HERE
THIS IS HOW TO DO IT!!! --you can,t open sketchup (.skp) files with pepakura designer, you have to go to the
file manu and go to save as and then it will ask you what you want to name the file and what type
of file you want to save it as, the default setting is set to sketchup models (.skp) << you have to change this
to the one right below it, which is sketchup virsion 6 (*.skp then reopen the file, and go to the file menu and
export it as a .kmz file (this is the default) then open it with pep designer.
if you have any questions feel free to ask, or if you want me to take screenshots of my computer while doing this, i can do that to.
another thing, i am running windows 7. but that shouldn't affect anything.
this is the
google sketchup warehouse < that is a REALLY good place to find stuff.
there are a bunch tutorials on you tube, if you need help on how to model with sketchup, i think it is pretty straight forward.