I can't count how many times I came across a 2D PDF drawing that I wish I can modify slightly. Over the years I looked at many different tools that would aid in turning a stale PDF into something usable. Enter ConvertPDFtoAutoCAD. I like how simple it is and how instant. I was pleasantly surprised at the quality of the output dwg file. So, if you're looking for a quick and easy way to turn those PDFs into dwg (or DXF by extension), then give this a shot. Of course, what really sold me on this service is that it's completely free and that's the best price.