Our kitchen has a couple of narrow 'spice cupboards' on either side of the built-in vent hood (first photo). These are really convenient except the top shelves are over 6' above the floor and my vertically challenged wife can't reach them. To make matters worse, she is under a lifetime ban from using step ladders or stools (don't ask why!). I solved the problem by making the shelves moveable. Photo 2 shows how I built the shelf insert. It slides out then down to the level of the second shelf giving her easy access to the contents.
The project was built from 1/2" plywood and a couple sets of full extension short drawer slides. They must be full extension with 3 rails so they extend far enough to work properly.
Pro: The new shelf inserts give easy access to short people.
Con:The shelf inserts give up 3" of width (4 layers of plywood and two drawer slides) reducing their capacity.
Step 1: Building the Shelf
These photos show how the shelf works. I first took out the fixed shelf that was in the cabinet. The slide out shelf serves as the shelf now. The frame of the cabinet is a lot narrower than the cabinet walls on both sides so I had to install wood spacers that positioned the drawer slides flush with the door frame. I then had to notch the frame the size of the drawer slide and screw the horizontal slides to the wood spacers. One slide near the bottom of the shelf was adequate. To these slides I attached pieces of 1/2" plywood the height and depth profile size of the new shelf box. I then constricted a shelf box with sides , a back and floor that is 1" narrower than the plywood side pieces. This box is attached to the side boards with 4 drawer slides.
To use the shelf it is pulled out of the cabinet, then lowered to working height.
An obvious requirement is a locking mechanism that prevents the shelf from descending until the user is ready for it. The last photo shows a latch I made from sheet metal. It is simply a long strap that is attached at the top of one side board (photo 3) and is bent as shown in photo 5 so it captures the bottom edge of the shelf box. I notched the side board a few inches up from the bottom so the latch easily clears the shelf.
Finally I made a couple tabs from Masonite that are glued over the ends of the horizontal drawer slides so they are hidden when the shelf is stowed and the cabinet door is closed.