I needed an adapter for my Garmin Transducer GT20-TM (which came with my Striker Vivid 4cv) to use it with my Scotty 141 Transducer arm. This mounts to the side of my pond boat. This design uses the hardware that came with the Garmin and the Scotty parts, so no need to dig through the hardware drawer.

It works great, and I initially printed in Duramic PLA+ but might change to PETG or ASA if this eventually fails.