I saw this idea else where but for a phone so I decided to design my own but for my Garmin head unit.

The mount clips on under the tablet mount of the Wattbike. There is a hole for a m4 screw which should cut its own thread. Lightly tightened this will secure the mount to the tablet mount.

Attach the extension piece with another m4 screw which again should cut its own thread.

You will need to print a mounting disc of your choice depending on what head unit you use (Garmin/Wahoo etc..). Fix this inside the recess how ever you like. I used the original screws from an old Garmin mount and piloted the holes through in to the extension piece, small enough so they cut their own thread.

I have printed the mounts face down using a small amount of tree supports just so I get the textured finish off the build plate.

I printed in PETG at 0.2 with 25% infill.