Ok, this particular project wasn't very big at all. In fact, it was so small that it seemed it'd be reasonable to do it indoors instead of taking it outside to the deck or the sidewalk. But it was messy alright. So in retrospect, taking it outdoors would've been a good idea. Except we'd have to run an extension cord for the blow dryer.
The project again is very simple - a cardboard box lined up with paper (note to self - tape the paper to the box BEFORE turning the blow dryer on), a couple of light-weight small balls (note to self -golf balls aren't particularly light at all), some paint (note to self - thin it out with water next time so it's not as viscous) and a blow dryer.
Even though I seemed to make every mistake in the book (actually, not in the book) preparing this activity, it turned out ok. M enjoyed picking the two colors (we only had 2 golf balls) - red and yellow. I was happy with the selection since it meant the inevitable mixing of the two colors would produce a lively orange and not the dreadful "preschool-special purplish brown".
Next, there was some figuring out of the angle at which to hold the blow dryer. It was kinda tricky 'cause the box had pretty tall sides (sounds like another note to self here...) Also, after using the blow dryer for the project, M used it to make his DIY Death Star toy skid around the room. Awesomesause.