One of the first caches I ever hid - a simple hidden-under-a-bench, magnetized container type - has been found and removed a couple of times, and I want to make something a little harder-to-notice.   My girlfriend suggested that a nano container be attached to one end of a short length of dowel rod, which is then inserted into a hole drilled into a nearby wooden beam, sanded flush and then painted so that it's hard to notice. To extract the dowel, you would wave a magnet over the dowel