I sometimes need to see on a map where in relation to the horizon an object may be visible from, for example to view a sunrise, sunset or an astronomical event. I can do this with an ordinary compass but my compass points image can be printed onto a transparent (OHP) sheet and it becomes much simpler to use as an overlay to a paper map. Right Click on the image to download as a GIF - easily prints on A4 size sheet or re-size to suit your requirements.
A note of caution - this device isn't designed to be accurate and must not be used for navigation purposes! This image is free but please mention that you got it from www.austintaylorphotography.com - thanks!