The legs' length is adjustable, each leg is connected to the desk by means of a plate with 4 screws on the perimeter. I want to lower the table's front legs so the table becomes slanted. I would like to be able to adjust the slant degree so placing wedges between the legs and the desk does not help me. I've been thinking on adding some kind of bearing between the desk and the legs but haven't found any bearing that would enable me to do that. Any suggestions?
I would use a hinge on each leg as the attachment, with the hinge facing forward. You want something reasonably tight so it doesn't shake the desk around.
You'll probably have to put a wood block on top of the legs, so that the legs and hinge both have something to attach to.