Run a stud finder across the wall at the approximate height where you would like to locate the drink holder floating shelf.
Mark the location of two studs that are nearest to the spot where you would like to mount the drink holder using a pencil. Place a level from pencil mark to pencil mark at the desired height for the holder and draw a level line to connect the marks.
Align the top edge of the 2- by 2- by 17 1/2-inch board along the line with the 2- by 17 1/2-inch side flush against the wall. Drive two evenly spaced wood screws through the board at each stud location using a screw gun. This will be used to mount the floating shelf drink holder.
Place the two 1/4- by 1 1/2- by 5 3/4-inch panels parallel to each other with the outside edges 18 inches apart with the 1/4- by 5 3/4-inch edges flat against a work surface. These are the sides.
Position the 1/4- by 1 1/2- by 18-inch panel across the 1/4- by 1 1/2-inch edges of one end of the sides to form a three-sided box. This is the front panel. It should sit with the 1/4- by 18-inch side flat against the work surface.
Spread wood glue across each joint and drive two evenly spaced finish nails through the front panel into the ends of the sides with a hammer.
Place one 1/4- by 6- by 18-inch panel over the top edges of the three-sided assembly and one over the bottom edges to form a box with the back side missing. These are the top and bottom panels. Apply glue to the joints. Drive finish nails through the top and bottom panels into the edges of the three-sided assembly every 2 inches.
Allow the assembly to dry 24 hours. Sand the entire assembly with fine-grit sandpaper until it is completely smooth.
Apply a wood finish with a paintbrush. Allow the finish to dry for 24 hours.
Slide the open back of the assembly over the wall-mounted board so that the back edges are flush with the wall. Drive four evenly spaced screws through the top and bottom panels into the wall-mounted board.