Step 1: Tools and Materials.
> A binder/ file folder... it needs to be material that snaps back to its original form after bending it
> A piece of paper and pencil (for the template)
> Scissors or heavy duty snips of some sort to cut the plastic
> Your hopper of course
> some kind of measuring device to use as a reference
Step 2: Make the Template 1
Then to make it easier on you, keeping it taped down, I cut the part sticking up into thirds down to the plastic.
After that I folded the middle part down as you can see in picture 2 and made a mark about a half inch above the lip/edge. With these rough dimensions you can create your template. Mine was about 7" (long) and 4 1/4" (radius/ height)... so not quite an exact semi-circle