Heart of Glass

Start up face with cobble-pebbles until placements could be made via the huecos. Careful with the cobbles. They could easily leverage out, tho some would leave behind excavated huecos with positive lip. Couple of big huecos at the top actually burrow through to the backside, which is a hollowed out big cave. Could anchor with long webbing(s) through those two huecos and over the top.