I make very small applicators from old cotton cloth and you can use small brushes. Of course, there is always the problem of errant glue sealing the wood and resisting stain or finish color. this sometimes can be carefully scraped or sanded away or covered with a little opaque color. I'll send some pictures of a little pad and the type of commercial shellac. Since it doesn't take very much finish to do the job and it is very thin, not entirely sealing the wood, so as not to seal it against the glue, the parts may often best be finished first, then glued together. The final finish shouldn't' be glossy or impenetrably sealed as it won't look realistically in scale for mast and spar timbers if it is. The thinned shellac is very fast drying if applied in very thin coats, so that handling the pieces as you coat them is not much problem. Just leave ample time between coats to allow the parts to dry thoroughly in between. When the finished surface is no longer cool to the touch between coats it will be dry enough to handle and re-coat. You can do as many as three or for coats in one session before leaving the piece to dry overnight. many thin coats are always the best approach. Stop when you get the right look, matte or very satiny, not entirely sealed. With the amber shellac, even thinned, the color builds up pretty quickly.