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Sheet metal (approximately 24 gauge, perforated in this case)
Basic layout tools (tape measure, square, ruler, or whatever you have on hand)
Step 1: Layout
The finished dimensions of my trays weren't critical so I decided to cut off the convenient, rectangular portion left over from a previous project and design the layout around that material. I cut out my working material using a hydraulic shear, but this could also have been accomplished using hand shears although that's quite a bit more tedious. Be careful not to cut yourself! Sheet metal can be deceptively sharp in its raw state.
Once I had cut my big rectangle into two smaller rectangles I measured and marked 2" cutouts at each of the four corners. I marked the piece using a Sharpie for the benefit of camera visibility, but layout marks can alternately be scribed using a utility knife. The utility knife offers the advantage of making much more precise lines and does not leave any noticeable markings on the project that may need to be cleaned up later.
Lastly, you'll notice that I left a tab on each of the corners rather than marking out the full 2" x 2" section. These tabs will be used to attach the sides of the trays later on. Again, no need for precision measurements here if you're not trying to build to a specific finished dimension. Just eyeball it and mark accordingly.
Step 2: Cutting Corners & Forming a Hem
Once the template has been cut to size, it's time to start bending. I started by forming a hem (or folded over portion) on the outer edges of the templates. These edges will soon form the top of the metal trays so it's important to do something that mitigates the sharp edges of the raw sheet metal in these areas. A hem is a simple solution that can be achieved quickly and enhances the look of the finished product.
The bends were started using the finger brake (aptly named so because it has removable metal fingers; not because it breaks fingers) and then I used a dead blow mallet to finish the job, making the hems nice and flat.
Step 3: Bend 2D Template Into 3D Tray
After the long bends are completed, remove the fingers from the brake in such a configuration that it will allow clearance for the vertical sides while also providing enough clamping area for the remaining short bends. As mentioned before, the tabs can either be located inside or outside the finished tray. I tried both, and found that locating the tabs on the outside of the tray did a much better job of covering any potentially sharp edges of the sheet metal. Bend all remaining short sides of the trays and that's it! The project has taken shape.
Step 4: Finishing