Maddox, who is doing a lot of interesting work on Shapeways such as these hinges, these rings that I love and this Iris. You can also check out his techy and interesting blog here. Now he has posted a video on his site that shows you how you can export from Alibre Express to Shapeways. Alibre is a free solid modeling tool and he shows you clearly how you can export to Shapeways using the STL file format. Check out the video here.