I found an interesting site with an utterly thorough teardown of the Advisor: https://goughlui.com/2016/01/15/tech-flashback-motorola-advisor-pocsag-5121200bps-pager/

I am going to use this info to help me create or repurpose an Advisor-style case. To begin with, I want to create a dummy interface in Adobe Illustrator that I can use to design my interface. What does every button do? What will be displayed on the LCD?

I took an image from that site, cropped it to the edges of the beeper, made it 81mm x 55mm (the dimensions of the Advisor) and then made a rounded square that size. I wanted the corner radii to be authentic and ended up going with 3mm. However, I noticed the bottom radii are different, a smoother and shallower curve. At this stage, however, it doesn't matter!