Reasoned:
Neither, Testors rattle can gloss, never had luck w/Future save clear parts.
Ditto Testor's, and I don't bother with clear parts... Crystal-clear parts... They don't look right on anything other than an Airshow bird... Real canopies on operational aircraft have myriad tiny scratches and scuffs... I just "polish" them enough to remove fingerprints...
Cleanup? Turn the rattle-can upside-down, give it a squirt to clear the siphon-tube, and re-cap...
As for the question, the best way to apply Future is to squirt it straight from the bottle onto the barracks-room floor, and use a sponge-mop to apply it, pushing forward only... Never back & forth...