I was looking for free or cheap modelling software , siemens do a free 2d software , solidedge , i don't know if it will work on mac's though. Delcam might do something to suit if you do a search.
Cheers folks, I did a lot more playing around and found that the BPT-Pro3 plugin for Adobe Illustrator did all I needed. I'm already really familiar with Illustrator so it sped up the design process massively and the plugin has some nice features. Here's some outputs: