Build a simple cross cut sled for your table saw.
Step 1: MDF
Cut 1/2" MDF to the length and width of your preference.
Step 2: Miter Bars
Rip miter bars to the exact width and height of the miter slots.
Step 3: Fasten
Place the miter bars in the miter slots and align the MDF over the top. Spot glue in place, flip the unit over and fasten with screws.
Step 4: Fence
Rip plywood the length of the MDF and to a desired width. I cut 6 pieces.
Step 5: Glue
Glue and clamp 3 pieces flat to create each fence.
Step 6: Fit
Slide the sled back and forth in the miter slots. The unit should be tight, but slide smoothly. Use a card scraper or sand paper to remove small amounts of wood from the miter bars until a desired fit is achieved. Then wax the bars.
Step 7: Fence Attachment
Place the front fence flush with the front of the sled and fasten on one side. Use a carpenter square to align the blade at 90 degrees to the fence face. Fasten the other side.
Step 8: Fasten
Finish fastening the front fence and attach the back fence as well. The back fence does not have to be perfectly aligned.
Step 9: Rip
Place the sled on the saw top with the blade in its lowest position. Turn on the motor and slowly raise the blade through the sled. Cut through the sled and fence.