Hi Petr,

It is here:

http://www.solveering.com/products/products_stl2step.html

The newest version actually works on OBJ instead of just STL.. It converts the poly's to NURBS planes..

It is hit and miss on high polycount models.. Low poly models have worked OK for me.. I had better results with the 1.4 version, but havnt loaded the 1.6 since I changed my OS.. It is a single clcik deploy WPF application, so you may need to be sure you are on windows with the proper .net stuff or something like that..

It's worth a try for what you describe.