Everything GardeningRotoplast & Self Watering Planter Systems

My neighbor says to use railroad ties but those might not fit with our look in the backyard. I was thinking more along the lines of some 2×6′s that are pre-treated to prevent rotting. Will this affect the chemicals that enter the soil? Are they dangerous? Does anyone have any good links to help with the building and prep work for a new veggie garden?
I’m think of making four 4×4 squares for the garden. Any tips would be great.