Here is a fascinating set of photos from the CIA archives picturing various spy devices. I've always been intrigued by the spy business, especially the equipment. Spy stories were always some of my favorites when I was young. A few years ago, I visited the International Spy Museum in Washington, DC. I only had a half a day to spend there, but could easily have spent a whole day. Highly recommended if you have the opportunity.
In particular, I found this photo of one-time use cipher pads quite interesting. For the latter portion of WWII, my grandfather's job was enciphering and deciphering secret messages to and from the Regimental HQ where he worked and the main command offices of Field Marshal Montgomery. I recall him telling me about a system similar to this, although I think for the most part, it wasn't on paper. They used a large number of one-time & recycled cipher algorithms (all memorized) in conjunction with a list of which cipher was to be used on each particular day. The lists were often changed and old ciphers were discarded and new ciphers introduced which then had to be learned.
I hope you find the ingenuity of these items as interesting as I do.
Tools of Tradecraft: The CIA’s Historic Spy Kit | Threat Level | Wired.com