I am building a low cost perimeter for the new team that we are starting next year, according to these instructions:
Low Cost Perimeter Instructions
All is going fine except one detail. The BOM says there should be 9 pieces of 11.5" x 41.75" hardboard, but when I look at the actual picture, it looks like there should be 12 pieces (3 for each of the four sides). Did I miss something or are the instructions wrong?
Definitely should be 12 pieces.
Awesome.
Welp, I guess I am off to the hardware store to get another piece of hardboard…
Kind of a sad but funny note, we built the low cost field as a homeschool team when we first started. someone stole it from the church where we were meeting the next week. We had it for one practice 
I guess they used it for their sprinklers
Who steals something from a church?!
Let alone a low-cost VEX field perimeter. I fail to see how that would be worth stealing.
Yeah, it was disappointing. There we sat with our clawbot and nowhere to practice
Yes, there should be 12. Wow I remember that mistake clearly. I can’t believe it’s been 2 years and vex still hasn’t updated it.
Also, IMO, I do regret making the field as it says. If you’re looking to transport the field with the mobility of the original field, than this works, but we didn’t need to. I think the easiest thing, (and with the least tolerances), would be to just find 4 pieces of 12 X 1, and nail them together. This will save you sooo much time, and give you a more exact perimeter compared to the low cost one. Even though it costed around the advertised $100, it took us at least an entire weekend to get ours put together, and the final product still has tolerances of ± 2.5" which is less than ideal 
As for if you made one out of the four pieces of wood, that field would probably cost around $30, take 20 min to assemble, and have tolerances of ± 0.5", very similar to the official field.
For a low-cost field perimeter we just bought four 12 foot boards and had them paired together with hinges, then we had the two sets of boards able to hook together to form a square shape. They are able to fit in our Suberban, and are much easier to set up than the Vex low-cost field perimeter.
we used hinged 2x4’s.