Save On Shipping Cost–Wrap 2 Boxes Together

Quote from usps.com:

Two or more packages may be mailed as a single parcel, if they are about the same size or shape or if they are parts of one article, if they are securely wrapped or fastened together, and if they do not together exceed the weight or size limits.

It works for UPS and Fedex too.

I shipped 2 baby gates before.
Product Dimensions are 3 x 33 x 30 inches ; weight 16 pounds. I wrapped 2 boxes together making them 1 6x33x30 box. Saved $20 shipping fee.

Here are an example.