When I am designing things, I tend to be thinking about re-usability of bits and pieces for some future project. All glue precludes that. However, I am rethinking my design philosophy because the most critical thing about a sled is that the runners remain absolutely fixed in place after the saw kerf is made in the sled. This insures that the saw kerf will remain parellel to the miter slot on the table saw.I always use 1/2" plywood for mine, no screws or nails, all glue fastening.
Have you used any plastic runners and if so what kind of glue do you recommend?