There are tons of ways to hold shelves, but I’ve never seen a way that easily lets you change the height of the shelf without removing the contents first, like Monterey Shelf claims their Speedy Shelf Strips can do. However, looking at the design it seems like it might be a little easier to raise the shelf than lower it.
The individual Speedy Shelf Strips are either 18″ or 24″ long and have interlocking ends to make longer strips. There are no extra pins or brackets to lose — the spring-loaded supports are integrated into the strips. The co-polymer polypropylene strips can be cut with a knife or saw and can be installed either with screws or nails. Monterey Shelf claims the strips held over 150 lbs. per shelf in the lab.
Speedy Shelf Strips are available in white, almond, beige, medium brown, dark brown, black, or custom colors upon request. You can find the 18″ strips in white, medium brown, dark brown, and black for $2 each at Eagle America, but pricing gets a little better if you buy more.