Working out of Buster Bailey’s snare drum book Wrist Twisters— one of the great books of technical snare drum studies, by the way— I came across a simple pattern I liked, and I wrote up some embellishments on it. The first pattern is the original, and the others are my variations:
Play each exercise many times as written, and with the stickings reversed. You can try to be strict about the written accents, or you may find yourself also accenting the added flams— it doesn’t matter. It is nice having the control to not accent all the flams. I would also work the first exercise alone strictly for speed.