The Pebble 2 works great, but the rubber at the buttons quickly breaks and the original buttons fall out. Here is a replacement ;-). I recommend to glue them in with 5min Exoxy glue.
Print upside down.
Add a brim, otherwise the parts will likely fall off.
After printing you may need to sand the inner button part to actually smoothly go in an and out.
Probably a higher resolution than 0,2 would be better, but I was too lazy to change my default values.