Somehow I just don't see that happening.
Like anything else, a lot of it is about quality work. When it's a pay site, then at least you can have "some" confidence that both parties involved are serious about the trade.
The only way I could see this "taking off" is if the site offered
VERIFIED CAD professionals, in specific fields, and with their own portfolios to verified companies.
Internet is anonymous, and giving somebody TIME and MONEY for a service that is of unknown quality at best is;....... retarded?
