For grooves that fit, check drawer-bottom stock
Not all sheet goods sold as 1⁄4 " stock measure a true 1⁄4 " thick. If, for example, you don't discover that until after you cut the grooves for 1⁄4 "-thick drawer bottoms, the rattle coming from your finished drawers will serve as a constant reminder. The lauan plywood above measures close to 13⁄64 ", thin enough to fit loosely. Even today's hardboard sheets measure too thin for a tight fit. The Baltic birch plywood, above, comes closer to a true 1⁄4 ", although it's typically manufactured in metric dimensions (1⁄4 " equals 6.35mm). For another source of 1⁄4 "-thick drawer-bottom stock, try MDF-core plywood.
—from the WOOD shop