Make the bottom shelf for your butcher block cart with 24-by-18-by-1.5-inch hardwood panel and veneer edging. Cut two pieces of 24-inch iron-on veneer and two pieces of 18-inch iron-on veneer. Lay each piece along the edge of your hardwood panel and press it on with a hot iron according to the manufacturer's directions.
Sand the legs and the hardwood panel with light-grade sandpaper. Remove all of the sanding debris with a damp cloth.
Stain or paint the four table legs and both sides of the hardwood panel. Finish with a coat of polyurethane for protection against moisture. Follow the manufacturer's directions for drying times and sanding between coats.
Lay the four decorative table legs side-by-side on a flat surface. Measure 10 inches from the top of each leg and draw a line. Place one L-bracket flush with each line and mark where the screws should be inserted. Remove the L-brackets.
Place an L-bracket flush with the top of each decorative leg, in line with where you marked the other L-brackets in Step 4. Mark the places for the screws. Remove the brackets.
Drill pilot holes where each of the screws for the L-brackets will be placed. Line up the brackets with the pilot holes and attach the brackets to the legs with wood screws.
Attach the hardwood panel to the lower L-brackets. Place the panel face down on the corner of a flat work surface. Invert the table legs so that you can attach the L-brackets to each corner. Remember to drill pilot holes before you insert the screws.
Drill pilot holes in the butcher block before inserting screws. Stand the cart upright and attach the butcher block to the L-brackets on the top.