just finished patching artex ceiling in living room about 18" sq after water damage,cut the damaged board out and fix new bit of board back in, to match the exsisting artex i used easy fill you can get it at any builders merchants for about £15 ideal for fine filling 100 times better than poly filler, so i mixed some up and spread it on the patch and used a brush, the small dust pan and brush type just dab it lightly and go over the edge by about 1" and after it drys just knock off the sharp points then paint it i have match it about 95% job done