Step 1: Materials
3 credit cards (I got mine when I stayed in a hotel, but any will do)
duct tape (you don't need more than 2 meters)
the tools required are:
scissors (make sure they are sharp)
pen (to mark your cuts)
Some paper might also be nice to make templates.
Step 2: Cutting
I used some paper and cut it to the width, then folded the paper in half. i then lined up the folded paper with the edge of the card and marked the middle with a pen. Then you can cut it.
Next, cut it to approximately the same design as the final picture. Try to get the two halves as close as possible in design. This will be where the bottom of your device rests, so make it accurate. The line is a fold line.