While upgrading our older kitchen cabinets, I wanted to add pull-out trays to the base cabinets. But I also wanted them to be adjustable so I could position them to maximize the storage space. What I came up with is similar to what old-time cabinetmakers used to use: notched shelf standards, as you see here. The vertical standards have notches evenly spaced along their length.
The drawer slide for the pull-out tray is mounted to a “carrier” piece. This piece has a small tenon at each end to fit into the notches, as you see in this drawing. To adjust the height of the tray, simply move the two carriers to a new notch. To make the notches, I stacked the standards together (four for each cabinet). Then I cut the notches along one edge using a dado blade on my table saw. This way, you can guarantee that all the notches will be level when the pieces are installed in the cabinet.