First you need to spend some time looking at museums and what they actually do for displays.
Here are two sites that currently have 1940’s displays in their museums.
Check out the exhibits at this new museum.
The curator talks you through one of the exhibits. What would you learn by participating in this exhibit?
Now that you have some ideas for your museum, you need to narrow down your topic.
Some general timelines and cultural events:
Think about what you want your guests to learn and experience about your topic.
The Library of Congress has primary sources they might “loan” you for your exhibit:
The US Holocaust Museum has great ideas:
You might check our the National Archives. Here is a link to propaganda posters: