And this box was born!
I didn't really use it as a suggestion box, but as a box to collect order forms and money. I designed it myself, without the use of another instructable. I made it from a Lowe's Large Moving Box and lots of Scotch tape. Then I decorated it with blue duct tape.
To make it, I cut one piece to the heighth and width I wanted for the tallest point of the box, then cut another that same width but a few inches shorter. I then cut two side pieces the same height as the first piece but only as wide as I wanted it. I taped it all together then measure how big the slanted piece needed to be. I taped it together and then measure how big the bottom should be, then cut out a bottom and taped it on. Then I cut a slot in the slanted piece for people to put order forms and money in. Later, I realized that no one would buy anything if they didn't know what they were buying, so I used these little metal things I found in my garage to hook some of my pieces onto the sides of the box. I also ended up adding a piece on top for the name of my "business" and also stuck some business cards in the top.
Thanks for looking!