What are you waiting for? Halloween is Friday!
Don't panic, some costumes/masks require little more than imagination, paper, and a pair of scissors. If you need some inspiration, visit our 391 section, or, visit Pinterest and use "costumes" or "masks" as a search term. There are enough boards to keep you browsing until next Halloween! Here's one pin that links you to "45 Adorable Toddler Halloween Costumes." And another that has animal masks made from brown paper (remember those brown paper grocery bags from pre-plastic days?)
While you're cutting, listen to the "Masquerade Suite" by Aram Khachaturian.