Lay the reclaimed footboard flat on a work surface with the bottom end facing you. This will be the back for the bench.
Place four reclaimed wooden wine crates side-by-side on top of the footboard with the open ends facing you. The bottom edges of the crates should be even with the bottom end of the footboard. The wine crates will form the base and seat for the bench.
Drive pan head screws through the corners of the inside of the crates into the footboard to secure them in place, using a screw gun. Drive pan head wood screws through the corners of the adjoining crates from the the inside of the crates. Stand the assembled bench upright.
Spray the entire bench assembly using a can of spray lacquer. Allow the first coat of lacquer to dry for at least 4 hours, then apply a second coat. Wait 24 hours before handling the bench after the final coat. For added comfort, you can place a seat cushion on top of each crate.