How do I re adhere the back plate to my pebble 2

I'd like to find the same adhesive or similar. I'm not exactly trying to make it water resistant like it's originally supposed to be but, I'd like to get as close as possible. If it helps it's plastic on both parts. And looks similar to a rubber cement type material.

. So that if I need to reopen my pebble 2 smartwatch at a later date. I'll be able to use a heatgun to open it.