I had to pull some of the parts into Meshmixer to cut out space for the sphere. Then I designed a custom plug to fit into the back part that would hold the tab on the sphere tightly so I could control orientation. I also took the time to adjust some of how the rear is put together so I could print the engine in a different color than the engine cowl.

Here are the spheres I used. I grabbed a mixed set so I could try a few different sizes. https://www.amazon.com/gp/product/B0776NHB88

UPDATE The original was by HMS82. It appears it has been taken down, which is sad. https://www.thingiverse.com/thing:3135742 It seems I missed the Antennae when I did the upload. Since you can no longer find the original, I have added the antennae to my files.

UPDATE 60mm sphere. And I want to remind people that this is not my design. I just remixed it. PLEASE DO NOT PRINT FOR SALE. I have changed the license accordingly.