Straight will work just fine... all depends on how fancy you want to get. I've seen some made with an angle on them... and replaceable center pieces with corresponding angles. This way you can make true zero clearance fences. Cut thru the center piece with the bit. Can cut 2 openings on one side, flip center piece over and cut 2 more. Bobj3(RIP) made several like this.. I'm sure the pics are still in his profile, but he's got so many to choose from I don't have time to go thru them at the moment.
Sometimes I wonder whether the world is being run by smart people who are putting us on
or by imbeciles who really mean it.