I've been on both sides of the fence. When I had to design something from the floor up, I would come up with a couple of ideas, then go and discuss them with a couple of trusted (no big egos) friends from Manufacturing and get some idea of how they could be made, in some detail. Generally most things were at either a concept or prototype level. Then after generating the maximum amount of information, the round table chat would happen again. By the time that Manufacturing actually had to make something, the key people knew what was going on and what was required. There were always problems, but by using this approach the problems were reduced significantly. When the project had to move to the next level (concept to prototype; prototype to pre production etc etc) the groundwork had already been done. The only time this approach went adrift was when we got a new, supposedly experienced CAD operator, with degrees coming out of every orifice, he had several, and who was sufficiently arrogant to believe that he was the sole source of knowledge and didn't believe in talking to the people who would be making his brilliant concoctions. He nearly caused a riot, and got "promoted" to IT System Admin or something demanding like that.
There are many ways of skinning a cat, some of them make a mess, some don't.
cheers
wakeup