I've designed a quarter turn clip for the Sony Smartwatch 3. Makes it nice and easy to pop out the sw3 and get it on your bike.
Tested off road on my mountain bike with no problems, so hopefully means its nice and secure.
Its fairly easy to push in, but hard to get out. My technique is to take the clip off the bike and use my fingers to push the back and sides outwards while my thumbs push the watch up from the bottom. Takes some getting used to but gets easier with practice and the plastic probably smooths out slightly.
Defiantly an option to sand/file back, the back edge of the clip for easier removal, as just the side clips should hold the watch in place on there own. Might do some more testing with some of the clips I've made and if there's any interest, improve the design slightly.
Also you can still use the side button on the watch if anyone ever uses that.