Things You'll Need
Instructions
Cut a treated 1-by-2 in two pieces, one six feet long and the other two feet long. Cut two boards 10¾ inches long from the short piece.
Rip the 6-foot 1-by-2 in half with a table saw or circular saw. Cut 12 strips 9¼ inches long from the halves of the strip.
Attach a 9¼-inch strip 1 foot from the end of a 6-foot treated 1-by-10 board. Match the ends of the strip to the edges of the board. Drill holes in the strip to prevent splitting, and fasten with 1¼-inch nails or screws.
Attach the remaining 9¼-inch strips centered every six inches, leaving approximately one foot of space at the other end (the bottom).
Attach the two 6-foot 1-by-6 treated boards to the opposite sides of the 1-by-10 with galvanized nails or 1½-inch deck screws to make an open trough. The strips of wood should be inside the trough: they are the riffles, obstructions to flowing water that are designed to trap gold and other heavy grains.
Fasten the short lengths of 1-by-2 across the open top of the trough with nails or 1½-inch screws. These help support the open trough and also serve as handles for carrying.
Attach a 10¾-inch length of treated 2-by-4 to the bottom of the sluice about a foot from the top end. Attach the sluice box to the narrow edge of the 2-by-4 with galvanized nails or deck screws.
Place the sluice in flowing water with its top end aimed upstream. Empty a shovelful of steam gravel and sand into the space in the top end and allow the water to wash the solids over the riffles. Pick through the sediment that remains on the downstream side of each riffle by hand to search for particles of gold. Repeat.