I have a property with a mulched bed next to a paved driveway that runs down-slope. The mulch is constantly washing out of the bed edge and onto the lawn when it rains. My solution is to install and edging material next to the pavement, along side the bed to keep water on the drive. I'll leave about 1/2 to 1" above grade. My choices are 5/4" pressure treated or "plastic wood" board or steel edging. The latter is my first choice but I can't find any. I found some colmet stuff online through AM Leonard but it is only 4" tall. I know I've seen some made 5" or 6" which would be much better. I'm thinking about talking to a local welding shop to see if they can get me something resembling these commercially available products. Has anyone done such a thing and if so, how do you install it with stakes? Is there a specific thickness I should shoot for (it will be a fairly straight run with a slight curve at one end)? Should I paint it somehow or let it rust? Any help would be greatly appreciated.