Pretty easy build, just used construction adhesive for the stones and a metal diamond blade to cut it

The product is by uberhaus called ledge stone wall slate, from Rona (Canadian store) but there are a lot of similar products usually called stone slate or veneer. I only really measured it to know it was square. I used the stone sections to find the size that would make 4 sections wide, 7 high and 1 deep. This reduced the cuts needed. I used 4 boxes, 2 flat and 2 corner.

Here are links to some of the things I use

Tools
Drill and Driver https://amzn.to/2ZhDNny
Circular saw https://amzn.to/2ZdsJaV
Sander https://amzn.to/36dtJgs
Oscillating tool https://amzn.to/2z1l1pP
Nail gun https://amzn.to/36ajOIN
Chop saw https://amzn.to/2zShZ7m
Pocket hole jig https://amzn.to/2WMxabf
Diamond blade https://amzn.to/2WHYS8V

Consumables
The best wood glue https://amzn.to/3g1koNk
Favorite construction adhesive https://amzn.to/2Ti6uga

Project materials
Similar fireplace insert https://amzn.to/2LBM4KX