Box it in however you fancy, anything that provides a line of sight barrier will help, more mass even moreso. But, within whatever you create, think about the airflow. The compressor needs an inlet to get cooling air and an outlet to expell it. The more enclosed you make it, the more separated the hot/cold airflows need to be, that might mean ducting within the box to stop warm air "polluting" the air the cooling fan draws in. All pretty simple but just bunging it in a box with a few random holes is asking for overheating. You also can't create a well sealed, convoluted, restricted duct for the cooling fan to draw through. They are generally within some loosely fitting shroud that'll just let air past itself if you restrict it too much. Also, don't forget the motor fan.