Cut rails to length and round edges with sandpaper. Make a mark every 154mm along centre of rail. Wrap a piece of masking tape around 9mm drill bit 10mm up from end. Drill a hole at each mark, only going as deep as masking tape.
Cut 9mm dowel into 55mm lengths. Squirt glue into each hole on rails and tap dowels into place.
Lay Masonite sheet face down on blocks to get clearance for saw. Mark width, then clamp a straightedge to sheet as a guide for base plate of power saw, making sure blade is on cutting line. Take a deep breath and cut.
Mark sheet edges in 154mm increments (as with rails in Step 1). Using a combination square, make a cross along marks, 10mm in from edge. Use this mark as centre point for drilling 9mm holes through sheet.
Cut legs, leg cross pieces, track supports and track support ends to length. Round edges of legs with sandpaper. Using Horse Track Diagram (link above), mark out, then cut winning post using a jigsaw. Lightly sand face of Masonite sheet to remove gloss, then spray all components with primer. Spray track with Dulux Enamel Topcoat in Jade, then spray all remaining pieces with Dulux in Vivid White. Leave to dry.
To create track support frame, screw track support ends to track supports. Put 1 track support at each end and 1 in middle.
Now construct leg assembly. The underside of leg cross pieces sit 155mm and 535mm up from bottom of legs. The top cross piece should be flush with inside face of legs, while bottom cross piece is set back a few millimetres, where rounded edge ends. Pre-drill, countersink and screw pieces together.
Join track support frame and leg assemblies by screwing through support frame ends into top leg cross piece. The underside of track support frame should be flush with underside of top leg cross piece.
Spread PVA glue along track support frame and lay track on top. Fix in place using 20mm nails. Glue rail assembly to track, lining up rail posts with holes in track. Clamp rail in 2 places until glue dries.
Screw through leg into end of rail, so it sits just inside rounded corner on leg.
Place round magnets on workbench, ensuring side attracted to rare-earth magnets is placed face down. Put a drop of super glue on each magnet, then sit toy horses on top. Leave to set.
Cut jockey stick and magnet blocks to size. On 75 x 90mm face of magnet block (see Jockey Stick Diagram, below), mark centre, then mark 25mm up from 90mm edge. Drill an 18mm hole, 20mm deep on mark, then glue jockey stick in place. Paint whole assembly and leave to dry. When dry, screw rare earth magnets to edge that will be facing up. Now you’re ready for the race!