Penn State published this list of websites that store STL files that can be printed on a 3D printer. Most of these are free to use. I found some Piper parts and knobs that could be printed for some of our radios. The STL files are a standard format for the design files. You still have to convert the STL files to a gcode for your specific printer. You do this with free software such as the Ultimaker Cura or Prusha Slicer software. Here are the links for the STL files:
- Cubify
Cubify is the central hub for all things possible with the 3D printed lifestyle. Many of the designs are advanced, but it is an excellent site to understand the possibilities of 3D printing. - Thingiverse
The grandaddy of 3D model sites, Thingiverse has over 100,000 models and is easy to add to and "remix" your own versions. There are groups you can join, rating systems for models, and challenges where you can compete to complete a task. - NIH 3D Print Exchange
The NIH 3D Print Exchange provides models in formats that are readily compatible with 3D printers, and offers a unique set of tools create and share 3D-printable models related to biomedical science - GrabCAD
GrabCAD, from Stratasys, helps "engineers get products to market faster by connecting people, content and technology. GrabCAD Workbench makes it easy for engineers to share files, work with partners and complete projects on time." - 3D Warehouse
From Sketchup, the 3D warehouse contains models ranging from printable nuts, bolts, and washers, to colossal buildings like the Burj Khalifa. These models are in the Sketchup format, but can be converted for printing easily. - Pinshape
A curated collection of 3D-printable designs. Some are free and some require payment to download. - Repables
3D printable file repository. - Yobi 3D
Yobi3D is a search engine for 3D models, indexing content from around the web - YouMagine
A community to share, remix and make better 3D printed things. - 3ders.org 3D printer and 3D printing news
comparing 3D printers, and other tools and resources about 3D printing, and for people interested in actually building 3D printers. - Reddit /3Dprinting
Main Reddit group of 3D printing, ideas, models, and discussion around printing. - SketchFab Cultural Heritage (Creative Commons)
A collection of public domain cultural heritage 3D models. For more information, please see Sketchfab Launches Public Domain Dedication for 3D Cultural Heritage