The Mark 3 Plotting Board was one of the main navigation tools for US pilots in WW2. In addition to the Mark 8 Flight Computer it helped visualize the flight legs during a mission, calculate wind drift and its correction as well as intercepts with other friendly and enemy flights or ships.
Reproductions and instructions for the Plotting Board are hard to come by. Thanks to @JDSwann and @Foxtrot (The Historical Aviator) and in our virtual squadron vVMF-214 "Black Sheep", both are now available for the aviation enthusiast and virtual (sim) pilot to learn and use for flight planning. We are still in the early (learning and) testing phase but it seems the Plotting Board can be used to much benefit if one wants to plan and fly a warbird mission in one of the big flight simulators (MSFS/DCS/IL2). Check out this page to learn more about JD Swann's Plotting Board App.
The Mark-3 Plotting Board is modelled in MSFS modules like the F4F Wildcat and the F6F Hellcat, albeit without actual plotting functionality. And the Plotting Board seems to be making an apperance in the upcoming DCS: F4U Corsair as well.
Here you can see and download the original manual for the Plotting Board. If you want to dive deeper and learn how to use it, I recommend you get JD Swann's free Mark-3 Plotting Board App.
Original manual for the Mark-3 Plotting Board with lots of example problems to use for learning the plotter. Download the PDF from here.
Photo and PDF courtesy of The Historical Aviator (Link).