Today, I've mostly been using a rotary tool to mechanically scratch paint off the base of a brick column. This has succeeded in giving me a sore back and knees, but as resolutely failed to do what I wanted it to.
When I've done this previously, the layers of paint beneath the surface were a pale colour, and even if I scratched too deeply and went back to the plaster, this wouldn't matter particularly. However, there seems to be some black paint under there somewhere, which means that the entire design is looking too dark, too obvious. (And also a bit like pencil lead, which ironically I used to draw the design on the wall in the first place. The way it looks currently, I really needn't have bothered with this time consuming scratching process).
When you get close enough you can see the layers of colour, which is interesting enough, but overall it's not working. Might try painting over it tomorrow, so all that's left is a scaring on the brickwork, a trace of the shape.