Multiple instances keyboard chop

hello
actually ive watched instancing tutorial which has been made by dear Mathew ragan.at the first of this tutorial I didn’t follow the way he set boxes.ive chosen4 boxes and merged them.now im working with noise top and don’t know how can I drop merged math nodes to sop merged boxes and turning them into a linear shape.may I kindly ask you to help me?

hi @P.MO_artworks - Matthew here.

Which tutorial are you working on?