To start, choose the width of the panels you would like to carry. I have a few measurement listed above and will use the 5×7 Wet Panel Carrier as an example to explain the reasoning behind the measurements. This way you can adapt these instructions to any size you choose. Once you know the width of panels (eg: 5×7″), add 5/16″ to the width (so a total of 7 5/16″) and cut your corrugated plastic sheet (across) the plastic ribs. The 5/16″ accounts for the depth of each side’s plastic sheet (1/8″ each) plus an extra 1/16″ wiggle-room so your panels aren’t an impossibly tight fit.
Cut all the way through the sheet and across the entire length, leaving you a section of corrugated plastic the length of your sheet and the width you chose. Place the other section off to the side for future projects.
After you’ve cut the width of the panel the next step is to cut the bend points. This is where approximations come in, as different brands of corrugated plastic sheets might have a different ribbing distances. For our 5×7 panel carrier example, we’ve already cut the width (7″ + 5/16″) so the first bend point will be the height: 5″ plus an additional 1/8″ wiggle room.
For the purposes of this tutorial, we’re going to start on the right side of the sheet and measure left. Measure 5 1/8″ and find the closest rib. We want to remove the plastic on one side of the sheet, leaving the other side to act as the corner of the box when folded.
Take your razor and gently cut through the top layer of plastic to the left of the rib but as close to the rib as possible. Once you’ve cut that, go two ribs over and cut through the top sheet to the right of that rib. After both have been cut, you should be able to angle the razor enough to carefully cut the center rib (between the last two cuts) and slowly peel that piece of plastic away, leaving a strip similar to the cut on the right side of the first image. If you accidentally cut into the backside of the sheet, do not worry, a little duct tape can be used to reinforce the corner.
After the first bend point has been cut, measure the base (depth) of the panel carrier. You will want to measure to the closest rib again. The carrier is designed to carry four panels, two facing in on the outside edges and two back to back in the middle, which means it needs to have a minimum width of two square dowels (3/16″ each) and four panels (1/8″ each). In the example sizes above I’ve recommended a depth of 1 1/8″ as that gives a 1/16″ buffer per panel so they can easily slide in and out without scraping. After measuring the depth to the nearest rib, cut two spaces out like the previous bend point, starting again to the left of the first rib and finishing to the right of the third rib, removing the center rib and the top layer of plastic.
Continue on and measure the height (5 1/8″) again to get the back of the wet panel carrier and do another “double space” cut like the previous two times. After that bend point has been made, measure the space for the lid (1 1/2″) to the nearest rib. Note that the lid is actually a little longer than base, as it will extend past the outside edge of the front and it needs to account for the extra space the velcro latch will take up.
Instead of being a “double space” bend point though, I would recommend a “quad space” bend point as shown on the left side of the first image. This will give the flap section hinge a little more flexibility when it comes to closing the wet panel carrier.
Finish the main section by measuring 1 1/4″ and cutting all the way through, leaving you with the second image.