Honestly, I'm not sure about prototyping capability on upwork. I guess a few of the freelancers there would have some capability of making prototypes -- especially if 3D plastic printing would work. Anyway, once you have a design you can put it up at mfg.com and get quotes to prototype it. Source: about 1 year ago

One way to go about it is create a Request For Quote, provide an outline and a set of deliverables and ask for quotes on a site like mfg.com. Source: almost 2 years ago

This -might- work for you: create a (free) GrabCAD workbench account (not the community item though they seem to be linked): GrabCAD - Workbench and then upload your file into a project of some kind. It will take a little while, but the file should import properly (and show/be available as 3D), as an assembly. You should (I have not tried this with an assembly) then be possible to go to the file and "Download As"... Source: over 2 years ago

Grabcad Workbench does this to some extent. It's not what I'd consider an elegant solution - all it does is save historical copies of your files - but it does work. My robotics team has used it for a while now, and it's free to sign up for. Source: over 2 years ago

I have been using grabCAD Workbantch (to share CAD files with my coworker). It has revision control and is free, but it comes with some quirks. GrabCAD Workbantch. Source: over 2 years ago

You can save files from GrabCAD as STLs. I assume you're aware that most of the parts can't be printed; O-ring seals, springs, the needle, screws, nozzle, etc. If you still want to download it, download GrabCAD Workbench and install it; download the Solidworks files (SLDASM and SLDPRT) to your PC, open them in GrabCAD Workbench, and save them from the 3D Viewer file menu. Source: over 2 years ago

Grabcad is a great source of models and you can convert most models using a free Workbench account. Source: over 2 years ago