I am a mechanical engineer by trade. I use CAD every day... Solidworks to be specific.
I also like to make a lot of my gear. I have never used CAD to design my backpacking gear. I have used it to design some wood working projects, and even modeled my roof to determine how much material I needed.
So, basically, I use it a lot and am very comfortable using it, but don't use it to make gear. That doesn't mean I won't in the future. I do see a lot of DIY tent makers on BPL using google sketch up. I have made tarps...and they are too simple to need to model it.
I've taken a vow of poverty. To annoy me, send money.