Wondering what you guys use for a strong flexible form. I plan on pouring a landscape curb around the back yard in the next month or two. Total length is going to be about 150-200 feet, 6 inches wide and 4 to 5 inches high and I only want to pour 25-30 feet per day so whatever I use needs to be strong and reuseable. The smallest radius is only 20 feet so the bend doesn't need to be that sharp. I looked at landscape edging but it doesn't seem strong enough to hold a smooth curve. The other option I was thinking was some Trex decking. Thanks.