As this year's political season came to an end, I started seeing a large numbers of corrugated plastic (coroplast) yard signs in the trash. There are plenty of these signs available -- used to advertise all sorts of stuff. Most of the time it is fair game to remove these signs from public space including telephone poles or the side of the road (see CAUSS for more info).
Here's a simple storage box design using a standard 18x24 inch sign.
Step 1: Tools
To make these boxes I used basic measuring, marking, cutting, and joining materials. You can use alternative tools as needed.
Other joining techniques I've tried include zip ties and rivets.
Step 2: Measure & Cut
From the short (18") side of the sign measure in and mark 1.5" and 7". From the long (24") side measure in and mark 4.5".
You'll make cuts at all four corners to remove small areas, as well as four cuts from intersecting points of lines you've marked out towards the short side. See image notes for clarification.
Step 3: Score & Fold
You'll need to score the remaining lines to prepare for folding - coroplast can be difficult to fold (especially against the grain). I've found the best tool for folding is a carpenter's pencil - it isn't sharp enough to cut the plastic and allows you to press hard.
All sides are folded up, with the extra 1.5 inches on the short sides being folded over the ends.
Step 4: Glue
Once you've folded the basic shape, get out the glue and use it to hold the box together. I use glue to attach the internal tabs to the short ends and then hold for 20 seconds. Then i fold the small end over, glue it, and again hold for 20 seconds.
Step 5: Finished
You've done it!
Here are a few other ways tried in the past using zip ties and rivets.