Just finished making a new crosscut sled. Cut a piece of 3/8" X 3/4" oak for the miter slot runner, carpet-taped it to the back of the 1/2" ply sled bottom and attached it in place with screws. Cut a piece if hard maple for the fence, screwed down one end and squared it up with my accurate framing square. Clamped it in place and installed another screw to secure the other end then put a third screw in the middle. Trimmed off the edge of the sled and test cut some wide plywood panels. They came out perfect. Flipped them over to check and they were still perfect.
First time I've EVER gotten it right on the first try.