Mounting external speakers for mobile use can be a PIA. I noticed that a local ham had squeezed a speaker between the headrest and seat in his SUV. I liked that idea & it mostly worked until it didn’t and would occasionally pop loose. I decided that between my modest machine shop and 3D printer that I should be able to fab something.
I grabbed a caliper and measured the diameter of the headrest supports and the distance between the supports and head over to my CAD program (Fusion 360). It took about 10 minutes to draw up a model that I liked.
The print time was about 90 minutes and it cost about $1.75 in filament. It is attached using 4-40 screws and the plastic holes are tapped for threads. My total time investment was under two hours.
73 de NG0R