Hello,
how can i model this triangles wall from the reference photo? thx 
From top left:
- subdivide (more than that)
- un-subdivide edges with 1 iteration
- triangulate
- select one vertical edge and select similar: direction, deselect sides, rotate edges cw or ccw
- bevel everything, delete faces
- extrude thickness, delete faces, recalculate normals
- select one front face, select similar: co-planar, new vertex group. Displacement modifier with a clouds texture, bevel modifier. Could add a plane behind if viewed directly head on.
