Icom ID-5100 Ram Mount + SP-35 Speaker Mount (Remix)

The remix link will show you how to assemble it (basically fill it will screws until it doesn't come apart).

Original author says he had to make it with ASA. I found that with PET it's a bit flimsy so I beefed up the thickness of the part. For the final version I made I did much more infill and 4 parameter walls instead of the default 2 and it seems rock solid now.

This skips the step of needing the Icom Icom MBF-1 - I modeled the RAM Mount directly into the design. I also make the part slightly thicker to hopefully negate the need to make it with ASA.