The original wall mounts from Sonos hasn't arrive in the shops yet. And I needed a quick solution so i could use my new pair of Era 300 as surrond speakers in my living room. 

Not a sexy design, but they work fine.

You need 2x M5 screews to mount the speakers on the plate.
And you also need to M4 screews and two nuts to mount the plate to the wall mount.

I printet them in 40% infil, and PLA+