To make a broad curved edge with formwork, simply bend the timber into shape and peg it in place. To make a tighter curve you need to do the job in stages. Start by pegging a broad curve in place. Then pour water over the timber to make it flexible. Once the water has seeped in to the timber, pull the formwork in tighter and peg it down. Once again, make sure the top of your edging is level and set at the height of your existing path.