Did you know that the Post Office has free Flat Rate Priority Mail boxes?
You can order Priority Mail Flat Rate shipping boxes free from the USPS, or you can stop by the Post Office and pick some up for free, no waiting in line. The have different sizes so choose the size that fits whatever you are shipping, you don't need a scale if it fits in the box it ships for 1 price no matter how much it weighs or where it's going (In the United States) and it's 2 DAY DELIVERY so you can still ship Christmas presents.
The cool part is if you create an account online at USPS.com you can create the postage and pay online and you get a cheaper rate than if you took it to the Post Office stood in line and had them ship it. You can print the Postage label on your printer and you don't need special labels just print it on a regular sheet of paper and tape it on the box, you can even schedule a free package pickup so you don't have to drop it anywhere. It doesn't get any easier than that, nothing worse than waiting in line at the Post Office.
Here are examples of size and prices click on the link for exact details:
Small box 8 5/8" x 5 3/8" x 1 5/8" $5.00 if you pay online, $5.20 if you go to the P.O.
Medium box 11" x 8 1/2" x 5 1/2" $10.50 if you pay online, $10.95 if you go to the P.O.
Large box 12" x 12" x 5 1/2" $14.20 if you pay online $14.95 if you go to the P.O.
There are more sizes and options available, these include Free Pickup and 2 Day Delivery