How to create a basic cross hatch pattern

1. Create a new document with the size: 600pt x 600pt.

2. Using the "Line Tool", click in the bottom-left corner of the artboard.
Insert the values below. (Length 600pt, angle 90°). Do the same for the bottom-right corner.
You should now have 2 vertical lines.

3. Change the stroke colour to an Orange and 12pt stroke weight.

4. From the appearance panel, select "Add New Stroke" and Choose Yellow & make the stroke weight 3pt.

5. Make sure "Path" is selected in the Appearance palette then go to the Transparency palette and change opacity to 40%.

6. Go to Object > Blend > Blend Options. Change to "Specified Steps" and "20"

7. Go to Object > Blend > Make

8. Go to Transform > Rotate. Enter 90°, press copy

9. Thats it. Throw a box in the background and your done.