Build your concrete form by measuring the length and width of your leaf. Saw your board into four pieces. Make two of the pieces 1 foot longer than the width of the leaf. Make the other pieces 1 foot longer than the length of the leaf. Hammer the four boards together with the double-headed nails. Fill the box form with No. 1 play sand.
Gently press your large leaf top side down into the sand. Remove the leaf and cover your impression with the dry cleaning bag. Press the leaf into the impression again and smooth out any wrinkles.
Mix three parts sand with one part concrete. If you are using dry colorant, add your colorant now.
Mix water and the fortifier. If you are using a liquid colorant, add that to the water.
Mix water and concrete by pouring the water into the concrete a little at a time. Mix until your concrete is the consistency of toothpaste. Press the mixture into your leaf mold, starting at the center and working outward.
Reinforce the concrete casting by pressing chicken wire down into the concrete. If the wire is too large, cut into shape using wire cutters.
Cover the leaf loosely with plastic and let it dry for 24 hours.
When the leaf is dry, gently lift it from the sand form and peel the leaf off the concrete. Set the leaf aside to cure. The curing process will take about 30 days.
Paint your bird bath using concrete sealant. When sealant has dried, place the bird bath in a garden where it's easily accessible to birds and fill it with water.