I made my way through this one better than I expected given my terror at the start, but I'm still not completely certain about the paintbrush bit at the end. I think I know where it must be, my only reservation being around there being exactly "two reversed" words. I can find ways to reverse different numbers of words and maintain integrity of the grid, depending on what counts as a word versus abbreviation etc. in Chambers--I was hoping it would end up being completely unambiguous. Does this sound familiar to others?