----SOLVED----
Thank you to everybody for your assistance. I managed to get to where I wanted thanks to instructions provided by @dual_sport_dork
Thank you, thank you, thank you!
Not sure if anyone can help me here. I am pretty lost and confused and wouldn't mind if someone could ELI5 something for me.
I've never used a real CAD software before yesterday night and I'm struggling a bit, I tried googling things but it's just sending me deeper into a rabbit hole of things I do not understand yet.
I'm trying to make this speaker enclosure I've seen just to do something with this shitty bluetooth speaker I have, so I decided to recreate the enclosure myself.
Long story short, I realized I kinda screwed myself after disassembling the bluetooth speaker and now I need to make a 2mm deep pocket on top of the case to snap in the buttons module. I don't really feel like starting the design again from scratch.
Anyway, as you can see in the attached image, I need to make a big round pocket on top, but both side panels are separate bodies so my pocket only goes through the main body and ignores the 2 other bodies.
I can think of other ways to achieve what I want but I'd really like to figure out a way to do it from where I am right now, if possible. I've seen the term shape binder and "union" in my searches but I can't quite figure it out.
Thank you to anyone who bothered reading this lol
EDIT: For anyone who might see this and is curious about how the enclosure is performing, I finished printing the main body and assembled it to test. Am still missing the side panels and I have to design some kind of flange cover for the driver but here's what I got so far:
Yeah I will keep that in mind for future parts I make. For now though since this is my first time using CAD software I'll stick with good enough hahah