Sometimes I am amazed at my own ingenuity. I was repairing the latch on downstairs neighbour's front garden gate which was no longer closing as it should due to...well, probably due to the ground moving because of traffic or tree roots or something. Anyway I noticed that the gap could be filled with a block of wood. Easy to find among all the bits and pieces I save for my own constructions. Sawed and glued two blocks together, drilled some holes, but then, problem:
Couldn't see where a hole should go on the lower half (too complicated to explain this). Scratched head for a while. Ingenius answer popped up: lipstick! Of course! Ran upstairs to fetch item, slathered red goo on face of old hole, pushed the wood tight against it and presto! imprint of hole marked clearly on wood showing where to drill. Job done.