How to Properly Use Hair Dryer to Remove Back Cover?

[TechnicGeek]

Hello,

I don't have heat gun but I have hair dryer.
I want to use it to remove back cover on Galaxy A5 2017 that I bought over 3 years ago so I can replace battery.
I understand that heat must be concentrated on the edges and with hair dryer it will be harder to do because it covers a wide area of surface.
So I wonder what material I should use to cover entire smartphone while keeping only one edge exposed at a time so I can bring hair dryer closer to it.

I guess some kind of heat-resistant material?

Thanks.

 

[TechnicGeek]

@Johnly So hair dryer is a better option despite every lab technician that I see doing repairs on YouTube uses heat hun?