Step 1 - Open up the Create Extension Dialog

There are two alternative methods of opening up this dialog.

Method 1 - CET

1. In CET, click on the Help toolbar option at the top right of your application.
2. Click the Extension Details dropdown option to open up the Extension Details dialog.
   
   
3. In the Extension Details dialog, click the New button at the bottom to open up the Create Extension dialog.
   

Note: This method will force the custom extension created in the base\custom\ directory instead of the extensions\custom\ directory if you choose the Folder name by the  button.

Method 2 - CET Operator

1. In CET Operator, click Dev Studio under the Developer section.
   
2. In CET Developer Studio, look at the list of folders on the left and select the folder that you would like to create your Extension in. This would typically be the workspace name\extensions\custom\ folder for external Extensions.
3. Click  + Add at the top to show more dropdown options, or right-click the folder > New.
4. Finally, click the Extension... option to open up the Create Extension dialog.
   

Step 2 - Fill in Extension Details

Fill in all the details of your new Extension. The package and folder names should autofill as you enter your Extension name, but you are able to change these accordingly. Also, add in the included packages and Extension dependencies if you wish, but these can be modified in the future when required. Lastly, check that you have selected the correct license type. Once you're done, press Save and your new Extension directory will be created.

Some required files will also be auto-generated within your Extension directory, along with some test files.

These files are must exist in order for your Extension to function and must not be renamed:

1. extension.cm
2. extension.xml
3. package.cm
4. library.cm

After your Extension directory has been created, you can restart CET, open up the Extension Details dialog, and turn on your new Extension. You should now see your Extension's toolbox available in CET.

Now that your Extension has been created, you can begin modifying and adding new files to expand on the functionality of your Extension.