Creating your own birdbath gives your yard a personal touch. Using a leaf to do so adds an extra element; one that harkens nature.
Create a mound of damp sand.
Form the mound roughly the shape you desire, both based on the leaf shape and the need for a bowl form. The bottom of the birdbath will be facing you as you work.
Lay the leaf on the mound of damp sand. Add and remove sand beneath it until you get the desired effect. Compress the sand well so you do not lose your shape when the cement is added.
Temporarily remove the leaf and cover it with plastic wrap to keep the cement from sticking.
Follow the directions on the bag carefully. Each manufacturer is a little different. Try to keep the mix thick enough to hold its shape and not run.
Spread the cement over the leaf. Try not to disturb the shape of the sand under the leaf. The edges should be 1 to 2 inches thick and the center should be about 3 to 4 inches thick. Build up the thickness gradually
Press the flange into the bottom center of the birdbath.
Cover the flange with cement, and press the mix into the four holes.
Allow the bath bowl to harden thoroughly (based on cement manufacturer's time recommendations).
Set the threaded pipe into the ground in your yard and carefully screw the bath portion onto the pipe.