When building curved railings, the author soaks 1x4 cedar rail stock in a temporary pool made with 2x4s and a sheet of black plastic.
After soaking, the 1x4s are steamed in a PVC pipe, with a wallpaper steamer providing the steam. It takes one steamer tank of water for gentle curves, and about two tanks to steam the lumber long enough to bend it to a tighter curve.
To speed production, the author assembles multiple bending jigs and bends as many rails at a time as he can.
The building jigs are assembled out of 2-by lumber and 1/4-inch plywood. Here, curved top and bottom rails are clamped to the jigs.
Assembly typically begins with longer branches left over from a previous section. Coped cuts are sometimes required where large branches intersect. To avoid splitting the branches, the author fastens them to the rails and to each other using galvanized 16-gauge finish nails.
When a rail section is installed, a second pair of curved 1x4 rails and a horizontal 2-by top rail are added to complete the assembly.