Do note this has to be mounted before you mount the cabinet on the wall.
The best way to mount this is to add a strip of double sided tape to the top of the bracket, install them, add the benchtop and then slide the whole benchtop with the brackets off. Mark the holes and remove the brackets. Drill your holes, install the brackets with screws and remount the benchtop on the cabinet, then mount the cabinet on the swall.
https://cad.onshape.com/documents/d17136e383d6a5e416301f20/w/ba15342ca8e47c14c094d625/e/7d3162af0a1fb4d904759940?renderMode=0&uiState=657ee2063ca65617d4b23ae5
The author marked this model as their own original creation.