----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:
OnShape is intuitive and easy to use. However it does have major downsides (for the free version): all your designs are publicly available and you cannot make money off of your designs without a license or whatever.
Also, due to being web-based you can log on and make stuff from anywhere, which is cool, and they even have an app. Obviously drawing things on a phone is not ideal but it does work—ive done it.
I wish it was FOSS but i always struggled with other applications and OnShape just clicked for me. It was originally recommended to me by a friend and now i recommend it to others.
(Haters please feel free to recommend alternatives—im not married to OnShape).
Oh, yeah no that will be a deal breaker for me hahah. I'd rather stick with FreeCAD in that case as I'm not a fan of web-based for things like that. I want my work to be local and I want to own my designs until I decide to share them.
Yeah, totally understandable. It bothers me a bit.
I dipped my toe into Solvespace for a couple of projects and it's not bad. As with anything it takes some getting used to, and there are things that it does better than freecad (and vice versa).
I will have to check that one out. I haven't heard of it.
As someone who has tried and used all of the popular commercial and free CAD software - Use what you like and works best for you.
I used OnShape to teach some rudimentary CAD skills to High school students just because it will run on the low powered school issued Chromebooks without problems and it fit the school budget - free. It was easy for me to pickup because I spent years using SolidWorks for a living as a toolmaker.
The most difficult part was getting the kids to use a mouse. Noticeable number are so used to touch pads and screens that they didn't even understand HOW to the the mouse.