To make a wooden patio table, you'll need wood that's been treated for outdoor use. Treated wood is not as appealing to insects as other types of lumber; it will also hold up better in the elements. Your table design will dictate how much wood you'll need and whether or not you'll need plywood or planks.
To make a slatted table like a picnic table, you'll need 4- to 6-inch-wide boards that are at least 2 inches thick to build the table-top frame and for similar planks to fit across the top. To make a tiled patio table, you can use a sheet of 2-inch-thick plywood cut to fit for the top of your frame. Four table legs will complete the frame for your patio table; make your own or purchase decorative legs from the home improvement store. You'll also need support braces, decking screws and a drill bit to make pilot holes so that it's easier to insert the screws.
To make a rectangular patio table with either a slatted or plywood top, assemble the four sides of your top frame as if you were making a box. You can use L brackets to join the corners together, or use 3-inch decking screws. The 4- to 6-inch-wide boards should be facing out and will become the sides of your table-top frame, with support boards running across the width of the table every 16 inches. Attach the four table legs to the corners of your top frame with L brackets or decking screws. To add the slats for a picnic-style table, attach the boards to each of the support beams along the top frame. You'll also want to attach the plywood top the same way so that it will not buckle over time.
Finishing a slatted patio table made from teak, redwood or other treated wood can be as simple as applying wood sealer to help protect it from moisture. Maintain your patio table with wood sealer at least once each year. To paint or stain your patio table, sand the wood with medium-grade and then light-grade sandpaper before you apply the finish. You can tile your plywood table top with ceramic, porcelain or slate tiles for a decorative finish. Thinset mortar is the adhesive you need to tile an outdoor patio table. To make a mosaic design, draw the outline on the table top, add thinset mortar to each section and place the tiles. Grout and seal the table top and you'll enjoy dining alfresco on your patio for years.