Varkon is a free CAD system and high level development tool for Engineering, Computer Aided Design and Product Modeling applications originally developed by Microform AB in Sweden.
It is now maintained and further developed by the CAD group at the Department of Technology at Örebro university in Sweden.
The GNU/Linux version is under the GNU GPL and available at no charge, while the current price for a Windows95/NT license is 875 USD. Support is available for all platforms.
Someone is using it on a Cray T3E supercomputer with 256 300Mhz 64 bit Alpha processors.
Check the Varkon home page at
http://www.tech.oru.se/cad/varkon/ to know more.
Though I have not yet tried it, the fact that SAAB uses Varkon to design its aeroplanes is enough to earn it a four star rating.
