I have been working with 3D printing for about a month and burned through several kilos of the plastic filament that is used for the extrusion process. The process is reviewed HERE in my Ramblin' Dan's Workshop so no need going into details here in the ham radio blog.
There are thousands of ready to print files available on the internet free for use in 3D printing. Also a lot that can be purchased. I take advantage of the free ones when they fit my needs or are just something interesting. What is really enjoyable is making my own 3D drawings from scratch.
Several 3D CAD programs are available here in my shack. The one I really like the best is called Rhinoceros or Rhino3D. Follow the link if you would like to know more about the software.
The call sign keyfob you see in the picture was designed in Rhino. Then exported as a 3D .stl (Standard Tessellation Language) file. STL is one of the poorest but simple 3D graphic formats and is widely used in 3D printing which is alkso called stereolithography. STL is pretty much the standard format in 3D printing but little else.
Of course designing something with my call sign was necessary. Look carefully (click to enlarge) and you will see the special feature under the call sign lettering.
The material used for this one is glow-in-the-dark PLA plastic. Rather ugly. A couple more in solid colors are in the works..