Need Help Making Realistic Blast Bags in 1/200

I've never built a ship that large that had blast bags. At 1/350 I use putty, Tamiya being my favorite. If you mask around the edges of where your putty needs to go, it goes pretty easily. You might even try impressing a fabric texture...

mike ashley, in his books, puts aluminum foil backing inside the turret and poking the barrels through. he fikks and shapes the area with white glue and paints. NOTE i use white glue as a filler. sometimes you have to do it multiple times because it shrinks when drying but works better than putty in some cases.

Leftie,

I've used this method to make  blastbags and canvas boat covers for models.  Carefully seperate 3 square of single ply toilet paper or tissue paper (kleenex), lay one on top of another and lay this on a piece of wax paper. Make up a solution of white glue and water. 2 drops water 1 drop of glue, you want the glue to be liquid and 'run freely'.  Paint the solution where you will want to put the barrle through.  LEt dry overnight (speed dry by use of hand held blow dryer works as well). Allow youself  EXTRA material, you can always cut it off later.  once dry lift the paer off the wax paper and if you feel the paper is stiff enough, if not paint it again with the solution.  Once dry them spray hair spray over the paper, stiffens it a bit more and allows you to hold the shape  Then you can push the barrle through them and push the part in the housung, cutting off what you don't need.  paint the color as needed.