[thisjustinm]

Another common name for these boards is "shower board."

One thing I noticed with the one I previously built was that different color / brand markers made a big difference in how easy it was to erase.

IIRC red and black Expo brand were the hardest to erase while green Expo would wipe clean even after a couple months (we left a couple of test marks on the board once we realized color made a difference to see how each fared).