Illustrator provides powerful effect 3D effect which allow user to create 3D text as well as 3D object with less effort. In this tutorial I will show you on how to create realistic 3D text. After tutorial you may create 3D text in less than one minute. Ok, let get start:
1-Type the Text
First you need to type the text. It is just normal text. You may already know how to do it. If you do not know it yet, you can see the following:
1-Set Stroke Color to None and set Fill Color to what color you like (I prefer orange)
2-Use Type Tool
to type a word 3D (You can use any font type, but in this tutorial I use Font Arial Black with Font Size 200pt)

2-Adding 3D Effect to the Text
In order to make text become 3D looking, we need to apply Extrude & Bevel effect. To do so:
1-Select the Text and go to Effect menu > 3D > Extrude& Bevel (Then 3D Extrude & Bevel Option window will load up)

2-Check on Preview (to see what happen when adjusting), then choose Classic from Bevel drop down box, Extrude Dept: 77 pt.

At this step the 3D text look not so realistic yet because only one default light is apply on the text. The 3D text will look like this.

So we need to add more light.
3-Click on More Option button to show more option
4-Click on New Light icon two times to add two more lights. Use mouse to drag each light into positions as you see in following image.

5-Then press Ok button

Now you get 3D text. I hope you enjoy this tutorial.
