Actually I found this 3D extruded text effects on a trendy magazine, it looks interesting so I open the Adobe Illustrator CS2 to try it out. I found out that it’s simple to achieve this effect. You can use this technique to spruce up your logo designs so they really pop on your business cards and business promotional items etc. Because this involved 3D extrude effect, so you have to have at least version CS of Illustrator in order to proceed.
At first, type out the text with desired font. In here, I’m using rounded text. Then hit Ctrl+Shift+O to create the outline of the text.
Next, with the outlined text selected, click Effect > 3D > Extrude and Bevel. A window appeared. Key in the values like what the picture shown below and hit OK. With the extruded text is still selected, now go to Object and hit Expand Appearance. The 3D extrude value is no longer can be edited now.
Now, you have to join them altogether. At first, ungroup them to the most basic level. Before joining, select the original text shape (not the 3D extruded), copy and paste it to above the canvas. You need this for final outcome. To ensure the pasted shape perfectly positioned back to the extruded shape, I suggest to Ctrl+C to copy and Ctrl+F to paste it on top. Then, use Shift+arrow key to precisely move it away.
Then, select all the shapes but not the pasted one you created just now, go to Pathfinder palette and click Add to shape area and expand it. Now the shape should be look like the first steps shown in picture below. If there is a lot of unwanted stroke point appears inside the shape, you can delete it manually.
After cleaning, select the shape and go to Object > Path > Offset Path, enter a value of 2 or 3 and click OK. A new path created outside the original shape like the center image below. Basically, the original shape can be taken off by now. You can drag it to the side of canvas if you wan to use it later. Then, put back the original text shape that you copied and pasted earlier on into the position. The simple 3D extruded text effect is now created.
Finally, you can add some gradient to the text shown below. Or you can also change the stroke value and many other options to play with. Tada! A 3D extruded text is finished!