Cut three pieces of straight 1-by-4 pine lumber as long as your saw table from front to back, minus 1 inch. Check the board for bowing by standing it on edge on a level floor. If the entire edge rests flush against the floor, the piece will work well, if there are any gaps under the board, choose another piece. Lay it flat on its wide face to check it for cupping in the same way. Make the cuts by hand or with a miter saw.
Stand two of the pieces on edge, 3-1/2 inches apart. Glue the top edges of these boards and position the third board on top of these two, wide face down, with its edges flush with the outsides of the other two boards. Nail in place with a 2-inch finish nail every 8 to 10 inches. Sand with a power sander and 100 grit sandpaper. This is the fence box.
Mark three lines on a piece of 1-by-4 pine, 2 inches apart. Bore a 1-inch hole in the center of each of the three 2-by-3-1/2 inch rectangles formed with a paddle bit. Cut along each line with the miter saw to create three 2-by-3-1/2 inch rectangles with a 1-inch hole in the center of each piece.
Glue and nail one of the rectangles inside each end of the three-sided box formed by the long 1-by-4s you nailed together previously. Make the pieces flush with the end of the fence box. Position the third one similarly, in the center of the box. You should now have a three sided box with a 1-inch hole running through its length to support a pipe.
Purchase a set of 1-inch pipe clamp hardware, available in most hardware stores, and a 1-inch galvanized pipe 8 to 10 inches longer than your saw's table. Fit the pipe through the holes in the rectangles you just installed and attach the two clamp ends to the ends of the pipe. Typically, these slip onto the pipe and are held in place with a set screw that is tightened against the pipe with a screwdriver.
Purchase two pieces of 1/4-inch thick clear acrylic such as Plexiglas or Lucite. These pieces should be 4-1/2 inches wide and match the length of your fence. Drill pilot holes every 10 inches along the center of the acrylic, using a countersinking pilot bit. Apply PVA glue to back face of the acrylic on the side opposite the countersunk holes, and position it on the 4-1/4 inch faces of the fence box.
Attach the acrylic by driving one 3/4-inch wood screw through each pilot hole. Allow the fence to set overnight for the glue to harden completely. Position the fence on the saw table using a framing square to align it perpendicular to the table edge, and a tape measure to check the distance between the blade and the fence. Adjust as needed and clamp the fence down by tightening the bar clamp snugly.