1/350 Bismarck Deck Masking for Swastika?

Check with the armor guys.  There are a number of circular masks used for road wheels on tanks.   WS

    you can use a pill bottle cap with a very small amount of white glue.  this will stop bleed of the paint.   if you need to remove anchor chains, small necklace chain can replace it.

sll

Metal circle template over masking tape, or a metal washer over masking tape, and cut carefully.

Metal circle template over masking tape, or a metal washer over masking tape, and cut carefully.

A sheet of spare black decals can be cut apart into 'bars' and made into a decal you need. Start with a 'X' & add the 'wings' or break it down into two bars '/ ' & ' \' The same approach can be done to mask it.

What about masking then attaching a blade to your compass to gently cut it out.

There are also specially made circle cutters available at craft and fabric stores.