MFG
Sewport
SolidWorks 3D Experience Collaboration Services
bttn
Wikifactory
Maker's Row
GrabCAD Workbench
ImportYeti
Voodoo Manufacturing
Zazzy
3D Hubs
Mockupify
Growmax.io
Muglaunch.com
Shapeways
Printful
Voodoo ManufacturingBased on our record, MFG seems to be more popular. It has been mentiond 2 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
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
Sewport - Connecting brands with clothing manufacturers
Zazzy - Design and sell your own 3D printed jewelry
SolidWorks 3D Experience Collaboration Services - Other Collaboration
3D Hubs - Airbnb for 3D printing
bttn - Press the bttn & Magic Happens™ (internet connected button).
Mockupify - Automate your print-on-demand product creation process