So, you just ordered 200 boxes from USPS because they were free and you've probably used close to none. Heres a neat project I made on how to utilize the smaller boxes. Don't have any boxes? Go to USPS.com and order some, they're free.
Step 1: Get a Box, Razor, and Packing Tape
In this picture I have two boxes because I wasn't sure how much I needed, get two in case you need another. Then get a razor and/or scissors and packing tape from officemax, walgreens or where ever.