This tutorial shows how to create a honeycomb pattern using pattern command under the object menu. Hex by row option is used to create a seamless pattern design. Blend tool is used to create a shadow effect to give a more natural look.
How to draw a fence in illustrator | seamless pattern design
This tutorial shows how to draw a seamless pattern in illustrator. The fence is drawn as an example. Once you create the pattern put it in your swatches panel.