For my prototype, I downloaded Autodesk Fusion 360 (free for 30 days), created the model and STL files that I sent to Shapeways and had 4 pieces 3D printed in a couple different materials (plastic) and colors. Used their coupon code for free shipping.
Total cost about 20 bucks, and turnaround less than 2 weeks.
Got lucky and the design was actually dimensionaly perfect. Got it done in one.
Then I used the same model in Fusion to created the drawings for the PPA. Fusion will output to PDF.
Learning curve is a bit steep if you've never used a 3D modeling program before, but there are tons if YouTube videos by Autodesk and others to get you started.
Bonus: I saw that Shapeways could 3D print in precious metals, so I designed a piece of jewelry for the wife and had it printed in sterling silver. That got me lucky, too.