1 Heavy Duty Steel Shelf Bracket 3/8" thick x 1-1/2" wide steel

SOLD AS SINGLES. Wood Shelf not included.
Heavy duty steel shelf brackets. These are made from 3/8" x 1-1/2" steel they have a holding capacity 120 Ibs. each. The wall leg is 4-1/2" on 6"-8" brackets and 5-1/2" on 10"-12" brackets. They come with four 1/4" holes and are bare unfinished steel. Sold as singles. Hardware not included.
6" bracket has a 5-1/2" shelf arm.
8" bracket has a 7-1/4" shelf arm.
10" bracket has a 9-1/4" shelf arm.
12" bracket has a 11-1/4" shelf arm.
Custom bracket sizes available on request.

There are many steel brackets sold on Etsy, with varying thicknesses and widths. Here are some comparisons for deflection (sag in the front for the bracket when weight is applied) These calculations are for brackets without a diagonal support arm.
12" long Bracket with 50 lbs. of weight applied.
3/8" thick x 1-1/2" wide- .13" sag in front of bracket.
1/4" thick x 2" wide- .36" sag in front of bracket.
1/4" thick x 1-1/2" wide- .49" sag in front of bracket.

Listed below is a reference guide of dimensional lumber you can purchase at your local lumber yard or big box stores.
1x6 actual size is 3/4"x 5-1/2"------ 2x6 actual size is 1-1/2" x 5-1/2"
1x8 actual size is 3/4"x 7-1/4"------ 2x8 actual size is 1-1/2" x 7-1/4"
1x10 actual size is 3/4"x 9-1/4"------2x10 actual size is 1-1/2" x 9-1/4"
1x12 actual size is 3/4" x 11-1/4"------2x12 actual size is 1-1/2" x 11-1/4"

FINISHINIG
I have had good results using this paint.
https://www.rustoleum.com/product-catalog/consumer-brands/painters-touch-2x-ultra-cover/satin?ls=249844&lc=Satin%20Canyon%20Black

You Can also wipe on Treewax Paste Wax if you want to keep the natural look. It dries hard with a clear matte finish. https://www.amazon.com/Trewax-Natural-Carnauba-12-35-Ounce-887101016/dp/B005SRV1PI/ref=asc_df_B005SRV1PI/?