Window board / banners / covering

[JABB]

I have a building with quite a few windows which has a history with the RAF. For security, I want to cover the windows and I had this thought I could put up B&W photos behind the glass of images which would have been seen in WW2.
I was thinking correx, foamboard or PVC banner.
What would the cheapest option be please? B&W print. Windows up to 5'x3' but most smaller

[StevieBee]

Cheapest would be to inkjet directly to foamex or similar.

There's also one-way vinyl. They uses this for full-body advertising on busses and trams. Allows you to see out but from the outside you see the image but can't see in. Easy to apply. Bugger to remove.

[JABB]

StevieBee said:

Cheapest would be to inkjet directly to foamex or similar.

There's also one-way vinyl. They uses this for full-body advertising on busses and trams. Allows you to see out but from the outside you see the image but can't see in. Easy to apply. Bugger to remove.

Is that the small dot mesh?
You can still see through if you press your nose against it?