How To Install A Curved Shower Curtain How Do I "bend" 3/8" Plywood ?

How do I "bend" 3/8" plywood ? - how to install a curved shower curtain

The intention of using to change a barrel vault over the installation of a shower .. After saok and bent screw faorm I built, then let dry. I want tiles as in "tile penny? Sun" smears "is evry 1 1 / 2" and then soaked in the tub .. Plywood (3 / 8 inch thick) consists of three 1 / 8 "number of threads. I did by cutting only the 1st layer .. I wanted to leave by two cut would not have enough wood to avoid cracking.

The ceiling is only 31 "square, and I can install on two separate bands for the shower to get through the middle .. it seemed easier to double in narrow widths ..

Wood was complete for 24 hours under water and began to spin. ButI need 31 "long strips to bend enough to create a 4 cm deep in the center.
two folds uncut w / grain in the same way () with curve

Any ideas on how to avoid violating their tracks when I bend? Any help appreciated (thank you very much:)