Have the sculptor or art dealer provide the dimensions and weight of the sculpture. These factors will determine the size and construction of the statue's pedestal. Also have the sculptor install 3/8-inch threaded channels or mounting nuts in the base of the sculpture. Alternatively, determine where to put the statue's base once the statue arrives. This solution allows you to change your mind if you do not like the location where you originally planned to place the statue.
Dig a trench in the soil where you will place your sculpture. This trench should be equal to the length and width of the sculpture, and should be between 4 and 16 inches deep depending on the weight of the sculpture. The most common depth for a statue foundation is 8 to 12 inches deep.
Pour a 3-inch layer of crushed gravel into the trench. Tamp down the gravel with a tamping tool to make it firm. The gravel pieces are unevenly shaped and will lock against one another so that they do not shift.
Cut scrap plywood to form the edges of a concrete form for pouring your base. The form may be only as large as the trench or you may make the form taller if you wish to pour a raised pedestal to give your sculpture prominence. Assemble the plywood so that it lines the edges of the trench. Nail the corners together with wood tacks and a hammer. Hammer wooden stakes into the ground outside of the boards to reinforce them against the concrete that will push outward when you pour it.
Mix concrete and water in a wheelbarrow with a hoe until it is as thick as cake batter. Pour a 1- to 2-inch-thick layer of concrete. Lay a sheet of concrete reinforcing bar mesh over the concrete to keep the cement foundation from cracking. Pour concrete over the cement mesh to the top of the box.
Place three 3/8-inch nuts over the end of 3/8-inch threaded rods. Insert the rods into the concrete in the corresponding location to the 3/8-inch mounting nuts in the bottom of the sculpture. Allow the concrete to dry and cure for up to a week before placing your sculpture on the foundation.
Arrange the sculpture over the threaded rods on the foundation. Insert the rods into the mounting nuts on the sculpture and tighten with a wrench.