Tape, a level, long ruler and a TON of patience!
We did a simple thick gray stripe about eye level across one wall, bordered on top & bottom by thinner white stripes. What a pain in the a$$! It took forever to get it all to line up straight. It didn't help that we live in an older house and the floors have settled and nothing is level.
If you are going to do an all-over pattern like that on a wall, I suggest wallpaper. Still difficult as you need to line it up straight, but seems much easier.