Hello,
I'm planning on adding some extra shelving to a bedroom closet without having to do too much work or modifications. One shelf spanning the entire length and a couple on the side. It won't be holding up anything too heavy, 20kg max. The door is 1700mm high so I might make the shelf shorter than 1730mm just so its easier to fit inside and maneuver.

I'm thinking of using cleats attached to the wall studs and door frame to support the shelf. Will 42x18mm finger jointed pine work?
Aluminum Angle instead of 2nd Cleat
Alternatively, could a 16x16mm Aluminum Angle attached to the door frame with a wooden cleat on the opposite wall do the same job? Not the biggest fan of how thick it looks with the pine and shelf together..
I'm debating on whether to use Custompine Particleboard Shelving or Specrite Formply. The particleboard wont fill the whole depth of the closet so I would need to use a different way to support it.