I needed some extra storage space at my 3D printers so I whipped up these bookshelf supports in Fusion360.
The supports have an opening that accepts 200mm x 16mm furniture panels (This is the one I bought) so you just slip the board in to the supports and screw them to the wall.
Printed them in BBL PLA Tough and so far they look and work great!
I used 6mm wall plugs and matching countersunk screws to mount them.
In theory you should also be able to mount them up side down for a different look.