This program allows you to create and distribute HVAC Diffusers by a number of rows & columns as per the user input.

The main dialog of the program is to specify the values.

Click on the Okay button. 

Specify the area to place the HVAC Diffusers.

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin. You may need to restart the Autodesk product to activate the app/plug-in. To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10/11) and uninstall as you would any other application from your system.

https://autolispprograms.wordpress.com/hvac-diffusers/