Not sure of how many exact hours it took me to do this, but it was over a week that I would work on it while watching Tv at night. I started counting how many buttons/beads I was using, I counted red, orange and yellow and it was 400+ so I stopped counting, but it was a LOT of beads and buttons in all. For the record I used a 12 inch embroidery hoop but you can go bigger or smaller depending on how much materials you have and your preferences.
Get an embroidery hoop of any size you want. A plentiful assortment of beads and buttons in the colors you want. A piece of fabric that fits on your hoop (I used black broadcloth), matching thread and a needle.
Put fabric on hoop make sure it is firmly on there and tighten the hoop. You will occasionally as you work have to pull on the fabric to keep it tight within the hoop. Thread your needle and start sewing!
Start on the outside of the circle and add your first color, use little beads to fill in the small spaces between buttons or larger beads. Then start your next color and so on and so forth. For very big beads or buttons you may want to go through their holes twice to make sure they are very secure.
Hang on wall, admire your work and you are done!