I started out by cutting out the sign parts and posts using scrap wood that I had in the pile. I used some treated and some untreated. Though they will be outside, it's for only one day, so using untreated wood won't pose a problem. For the sign part, I used 1x6" boards and for the posts, I happened to have a decking board that had been cut long ways into a nice post size. I made each sign in the shape of an arrow, using the corner of a sheet of paper to trace the angle. I cut out each piece using a jigsaw, then screwed the post onto the back of the sign using two screws. Make sure to pay attention to which way the arrow is pointing.
I designed my wording on the computer, then printed it out. I then traced the letters over the wood with a pen, using a lot of pressure.
This left a nice little indention, which I then filled in using a black paint pen.
And that was seriously it! If you wanted to, you could paint, stain or seal the wood, but I opted to leave mine natural for simplicity's sake.