Greetings:
I have "discovered" a way of crinkling the fold-over-flat-to-the-CBoo-butt tail. It may be old hat to you but, if not, then I'll not have wasted your eyeball grease.
After completing your roll-up of the PPatch do NOT pick up the now-cylinder-tailed PPCBoo to crenulate the tail by hand. Instead, lift up your rolling-fingers, put the index finger centered on the CBoo's rear end (other rolling fingers are on the CBoo body proper), press down, and roll forward a couple of turns. Your index finger's downward pressure causes its flesh to overlap the CBoo's rear edge, resulting in the protruding PPatch tail cylinder's forming a perfect-and-instantaneous crenulation (crinkle/fan-fold).
Now, to finish it off, simply pick up the nearly-finished PPCBoo, hold it base-down on a hard surface at a 45 degree angle, then press down it lightly with your off-hand index finger as you roll it forward (along its base edge) with your main hand ~~~> let your push-down off-hand index finger follow the roll, but drive the rolling with your main hand. Bring it to vertical slowly in two-to-three turns. Shazayum! The crenu-folded base will be flat and packed and your PPCBoo will be ready to set, upright-and-base-down, on your piece of plastic window screen material, which approach allows the PPCBoo's base can dry at the same time that the sides are drying (the PPCBoo's weight also holds the crenulations folded flat until drying locks them in place).
At any rate, that is how I do it.
Zeek