I once took photographs of text with fixed focus point 'n shoot by sticking a +3 close-up lens onto it with Blu-Tac. Since the focal length of a +3 lens is 333 millimetres the pictures will come out sharpish if the camera lens is focussed on infinity and the camera with close up lens is about 333 mm from the subject. Getting the distance was easily done by tying a piece of string to the camera and leaving a free end 333 mm long.

The end of the string goes onto the subject, the camera is pulled back until the string is tight, hold steady, move the string aside, shoot! The technique works well except for the awfully approximate framing.