The "slate" is from reclaimed old chalkboards that were purchased at http://www.noreast1.com/

It is not easy to find real slate chalkboards these days. They were cut to size with a skill saw that had a diamond blade on it. Go slowly and set the saw depth to a minimum. Use a honing stone to smooth the edges later. The "buttons" are screw caps and seats in stainless that were sprayed gloss black. https://www.roundcaps.com/Screwcap%20Sets%20with%20Dimensions.htm

The slate is set off the wall with a 1x piece of wood that was painted black and anchored to the wall studs - this gave me the ability to fasten the slate at the corners.