I want to build a concrete boarder curb for my back yard lawn area. The curb will be curved so I'm assuming that I will form it with bender board. What type of bender board should I use? Also, how deep should I make the curb? Should I pour concrete lower than the bottom of the bender board? I haven't done too much concrete work but I think I can handle this project. My patio is stamped concrete and I would like to color the curb the same color. I'm not sure how to apply the stamping colored powder. Any suggestions would be appreciated.