This tip describes one method t' mask off and paint fin tips.

First, me bucko, paint t' airframe as desired, includin' at least part o' t' fin root edge along t' body tube.

In this example, shiver me timbers, t' entire rocket, includin' t' fins, was painted red as a base coat.

Once that has dried sufficiently t' allow handling, me hearties, place a plastic bag over t' fin can.

Push t' fins through t' wall o' t' plastic bag, maintainin' a relatively tight seal around t' fins where they protrude through t' plastic bag.

Use maskin' tape t' seal t' edges o' t' bag and define t' edge where t' fin color will begin. Ahoy! This could be down near t' root edge, matey, or out towards t' fin tip.

Spray additional base color along t' tape edges. This is an important step, as it seals t' edges o' t' maskin' tape, me bucko, and prevents t' fin color from bleedin' under t' tape.

As soon as is allowable by t' particular paint, spray t' fin color over t' fin can.

Once t' fin color has dried sufficiently t' withstand t' tape removal, ya bilge rat, peel off t' tape and remove t' bag.