Something I started as a challenge a few months ago was to do a conventional accented single paradiddle (Rlrr, Lrll) but be able to move the accent, after every 2 measures of each.
(Rlrr, Lrll) x 2, (rLrr, lRll) x 2, (rlRr, lrLl) x 2, (rlrR, lrlL) x 2
I have since progressed to repeat this...