postcard.co.uk

Can anyone help me. I have what looks like an old postcard of The Great Exhibition 1851. It opens like a bellows, and when you look through the hole in the front, it gives a 3d image of the inside of the Crystal Palace. Thanks. Steve.

Sounds like an interesting item but it won't be a postcard as Picture Postcards were only in use in the UK from 1894 onwards.
It will come under the general category of Ephemera (Printed Items). Try the Ephemera Society ...
http://www.ephemera-society.org.uk/