HOME IMPROVEMENT : Building Sandbox Like Child’s Play : Put one together with patio blocks, boards, fasteners and, of course, bags of sand.

Children of all ages love sand. Here are instructions for an easy-to-build wood sandbox that will provide them with years of fun.

A hammer, saw and screwdriver are all you’ll need.

The base for the box is made of patio blocks, available at building product or home centers. The box itself has no bottom, so that rainwater can drain out. Get at least 21 8-by-16-by-2-inch blocks for the base. A lid allows the box to serve as a low play table and also acts as a barrier to pets.

Built of Lumber

The box and lid are built of lumber. To minimize waste, buy the lumber, all 1-by-4-inch stock, in standard lengths. You will need 7 8-foot lengths, 1 10-foot length, and 2 12-foot lengths.

Redwood needs no wood preservative because the wood resists rot, but it is expensive. Pine or other softwood is cheaper but should be treated with a nontoxic wood preservative or paint.

Saw the wood into these pieces: 6 48-inch side boards; 6 26-inch end boards; 10 12-inch uprights; 14 28 1/2-inch lid boards, and 2 46-inch lid crosspieces. All the lumber is 1-by-4 inches.

Hardware and supplies:

--Four mending plates with 1/2-inch screws.

--Galvanized nails: 2-inches and 2 1/2-inches.

--Two 36-inch lengths of 3/8-inch steel curtain rod cut into six 12-inch pieces.

--Three 50-pound bags of washed white sea sand, available at building or home centers.

Steps of Assembly

How to assemble the box:

1--Use 8-foot pieces for side boards, lid crosspieces, end boards and the uprights. Cut side boards and lid crosspieces first. Then cut end boards. Use the leftover 3-foot lengths for the uprights. Use the 10- and 12-foot lengths for lid boards.

2--The sandbox is 12 inches (or three boards) high. Nail three uprights, evenly spaced, to the end boards and two uprights to the side boards. Use 2-inch nails driven from the outside. Hammer two nails through the uprights into each board.

Stagger the nails to prevent splitting. The nail points will project 1/2-inch from the inside surface. Hammer and bend these points down and into the wood (clinch-nail) so they won’t scratch. This will also make a stronger bond.

3--Assemble the completed sides and ends. Fasten the sides to the end pieces with 2 1/2-inch nails.

4--Position lid crosspieces 10-inches apart on the lid boards. Adjust the crosspieces so they will fit inside the ends of the box. Clinch-nail the crosspieces into the end boards with 2-inch nails driven from the outside. To reinforce the lid boards at the corners of the lid, attach mending plates outside the crosspieces with 1/2-inch screws.

5--Lay the patio blocks. Set the box on the blocks. Anchor the box by driving two rods into the ground on each side and one at each end in the spaces between the blocks.

For information on the source for this article, write Reader’s Digest, P.O. Box 700, Pleasantville, N.Y. 10570.