Free CAD/CAM Software Options

Hello all, names Craig and Im not really new to the CAD or 3D world, but as far as producing something that will be manufactured using software I have barely tinkered with is extremely overwhelming. In a nut shell Ive been kicking around an idea or 2 for a few years and every time I present the idea to a manufacturer they want drawings. That would be fine if they were just talking an artists render point. I am an artist, specifically a tattoo artist, and have a huge background in art. But every piece of 3D rendering or CAD software Ive ever meet with really intimidates me for some reason. I have very extensive knowledge of Adobe Photoshop and use it all the time. Illustrator not so much but I know how to use it. Along with plotting software I use WinPC Sign. So can I get some suggestions on what would be the best free software to produce the production drawings Im needing to do, also the easiest free software to do the same and any other info you guys can give me. Im tired of these ideas going to waste and Im starting to see others coming up with extremely similar products. I really want too do this.Thanks in advance to all!!