Following are the steps to create a 3D ball using Photoshop

Step 1
Take a new file (Shortcut Ctrl + N) in Photoshop. Press Ctrl + Shift + N to create a new layer or this can also be done by clicking on the 'create a new layer' icon at the bottom of the layers panel. Select a dark color in foreground color box and press Alt + Delete to fill the layer with dark color.
Step 2
Create a new layer as shown in the first step. Select the Elliptical marquee tool (Shortcut key M) from the toolbar, with the shift key down draw a circle on the layer. The circle is marked with a dashed line.
Step 3
Set your favorite color in foreground color box , I selected red. Now press Alt + Delete, the circle is filled with red color.
Step 4
Create a new layer as shown in the first step. Now use brush tool to give some shading. Click on brush tool on the toolbar. In the option window give the settings as seen in the image below.

Press D to set the default colors and paint the circle along the corners as shown in the image below.

Step 5
Create a new layer as shown in the first step. Press X to exchange foreground and background color. With white color as foreground color, and with the same size of brush shade the edges of the circle and also on the top as shown in the images below and your image is ready as shown below.

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