Well, this one’s an interesting glitch. From GamingReinvented:

  • Complete the Great Sky Island without collecting any materials
  • Get the Hylian Shield (or alternatively, any shield with a price value)
  • Speak to a shopkeeper
  • Say you’ll sell them items
  • You’ll end up in the shield tab
  • So just sell them the shield! It won’t disappear from the inventory, so you can just repeat until you’re rich

In other words, not collecting ANY materials and any shield that has a value in Rupees completely breaks the game and nets you infinite Rupees. Try it out! My money’s on Nintendo patching this relatively soon, though. (No pun intended.)