Figure 1 Begin with a base color in the shape of leaf
(click image on left to view full size)

Start by creating a 72 DPI new document with a white background. Because this technique requires lots of ram, low resolution like this will keep the file sizes down and speeds up. Select a leaf shape using the lasoo tool. Using your paintbrush and/or airbrush tools, fill it with leafy colors. I've made a simple green leaf with some slight yellow feathering at the edges for simplicity. Your leaf can be any colors you like.

Figure 2 Make a new channel
(click image on left to view full size)

Using the channels toolbox, make a new channel. It will want to call itself "#4". The image turns black and your leaf shaped selection remains active. Fill the selected area with white. This channel will be used in the future to select the leaf. More on that in a minute.

Figure 3 Make a texture channel
(click image on left to view full size)

Click and drag the new channel, #4 onto the "create new channel" button next to the "channels trash". This will make another channel, an exact duplicate of "#4" called "#5". This is where your texture map will be made.

Figure 4 Create your texture map
(click image on left to view full size)

Inside the white area of channel 5, use your airbrush tool to make simple shaded surfaces that look like the shapes of a leaf. I deselected and then, using the lasso tool, I selected just the right side of the leaf to make a paint mask to give the leaf a central spine. Remember, white is the high areas and black are the low. Once you're satisfied with the texture map you've made, deselect and then, holding down the keyboard command button, click on channel #4. This will select that channel. In a complex illustration this can be a valuable technique in and of itself.

Figure 5 Make a new leaf layer
(click image on left to view full size)

Click on the layers toolbox tab to bring it back up. Create a new layer. Copy and paste the leaf color and shape onto the new layer. I like to do this mainly to keep this object separate from the rest of the illustration in case I want to move it later.

Figure 6  Lighting effects for your leaf
(click image on left to view full size)

This step is the turning point of this tutorial. Under the filters pull down menu, under render, select lighting effects. A dialogue box similar to the one above appears. Set the properties and attributes similar to what appears in my screen shot. The MOST important step however is to select channel #5 in the texture channel area. This is what makes the texture. Experiment here with different types of lights, directions of lights, colors of lights, ambience, material properties (are leaves plastic or metallic?) Click ok and see what you get. If you're not satisfied, undo it and try again. It's never right the first time.

Figure 7 The finished leaf
(click image on left to view full size)

It might look like this. Your results may vary and that's ok. It's now ready to add a drop shadow or be inserted into a new scene.

The 3D Leaf

Here are a few other objects created using this technique. The range of 3D fakery possible with this technique is almost limitless, have fun. To see those examples, click here.