Step 1: Materials needed

Picture of Materials needed
As far as materials go, the most important part is the 20"x13" wooden Barrel Tub. There are many sizes, but my experiences tell me that tomatoes typically need a deep root base. So I found the 13" barrel best accommodated this. The tested variation in step 10 gives a little info regarding a smaller 7" barrel that I originally tried and how I made it work.

1 20"x13" Barrel
2 20"x13"x3/4" pieces of wood for a backing. Use Redwood if you want to be exact, but I used some scrap doug fir. Smaller pieces can also be glued to make the final size.
1 bottle of Wood Glue (water based, not polyurethane)
8 #8x1/2" pan head wood screws for securing metal banding
1 Box 1" 1/4 crown pneumatic staples- If you do not have an air compressor these can be replaced with 1 1/4" finish nails or #6 x 1" screws

Tools make all the difference in a project. I'll explain what I used, but will also try to make suggestions on safe alternatives.