Tell us about yourself!
You're definitely going to need a few piezo disks to really be able to use the output for anything (like LEDs). After you have run everything through the rectifier, you can wire that output to the input of say, a rechargeable battery pack. Of course you're going to have to take the battery pack apart to do this :)
Well, you can't really buy the rigid disk in a rectangular shape. There are piezoelectric "flaps" or "sheets" that you can buy, but I think you may find them to be challenging to apply as used in this instructable. They're also usually pricey as they're typically used for more sensor-like applications.
Hello! I have updated the instructable. The files you're looking for are now attached to the last step. If you'd like any of the other files (STLs, reference materials, etc.), comment back here and I'll get those to you.Happy building!Ryan