Hi, Ned. I know this doesn't answer the question you asked, but I have made imitations of the Festool guide rails by fashioning the base of the rail from nominal 1/4" cabinet-grade ply and the raised part from UHMW. A couple og strips of UHMW tape on the top of the base would probably have reduced the friction between the tool and the base. I used double-sided tape to attach thin, sticky carpet padding to the underside of the base to keep it from sliding in use. You could probably omit that if you were planning to permanently attach your shop-made rail to a jig.
It took a little fiddling to cut the UHMW strip to the proper width so that I didn't have to adjust the set-screws on the saw or router, but other than that, it the rails took little time or effort to make and worked quite well. Sometimes I even regret getting rid of them because they were a bit stiffer than the aluminum rails and sometimes that stiffness is an advantage.
Regards,
John