This is a remix from brunoblutut. I modified that STL to make it more robust on the clamps and the possibility to mount it on the handlebar or the stem. I ended up with the following settings for the (iGPSport_mount_1.stl) which worked for me, but you can try removing support and brim.
iGPSport_mount.stl | 403.3KB | |
iGPSport_mount_1.stl | 430.4KB |