What kind of ovens do you folks have?! Never had a bumpy cake problem in my Miele or in my Thermador… 
Mine is probably operator error rather than oven error Although this particular oven baked level cakes in the beginning. Starting to think my floor is sinking toward the middle of the room. I fixed my problem by stopping baking cakes. I was always the one eating all of it anyway…
As you know, matter does not disappear. The sinking floor and the unmarterialized bumps on cakes end up somewhere… me thinks on our middle sections.
I hadn’t heard of the cake strips before. I use dental floss to even the layers if needed.
“It’s physics.” (A claim I like to make for lots of things. 
) The outside of the cake pan heats faster, cooks faster, than the inside. So the cake rises more in the middle. The strips are meant to slow the heat exchange to the outer rim. Alternately, the core (the cone or flower nail thing you can put in the middle of the batter) draws heat to the center.
Neither works for me. My cake leveler was cheap, on Amazon. Or use the cake turntable and hold a knife steady.
i just turn one layer upside down then put the icing between the layers such that the layers are bottom to bottom, and the top layer is right side up.
^ the way my mom taught me, yep. I’d imagine Consolation reminding us not all fillings will hold up a top layer the way a stiff icing can.
DH had heard about the core heaters. ORdered some and he said, 'Nah." He said he’ll stick to adding more frosting to level out his cakes. (The health insurer surely must hate him for how he feeds his colleagues!)
Aren’t you supposed to hollow out the cake layers so more filling can go in?
Not necessarily. Boston Cream Pie, maybe.
My cakes: minimum cake, maximum filling. And real butttercream frosting. Lots of it.
Well, I have magicake strips AND a cake leveler. 
The strips also let the cake rise a little higher, and they are so easy to use, why not? I usually end up using the leveler only to cut each layer into two layers so that a 2-layer cake becomes a 4-layer cake.
If you are making a tiered cake, you really want even layers. And @lookingforward is of course right about the fillings.
The big problem that most people have is if they are still using the old el-cheapo light weight cake pans with slightly slanted sides that many of us grew up with. They make a cake a real B&$)! to ice on the sides, and the layers tend to slip if the icing isn’t like cement.
@BunsenBurner , what recipes do you use for the cake? And what do you mean by “real” buttercream?
@GRITS80 I looked at your link. Too funny that whoever did the illustration chose to show a domed cake! I guess they thought that a nice flat top wouldn’t look nice, or something.
If your cake layers are really uneven, just trim them like the pros do.
When I frost me cakes, both layers go upside down. That way, I get a flat top instead of a domed top, I really haven’t had much issue with really uneven cakes. Maybe it’s the pans I use, oven (Thermador), or recipes.
Consolation - I have to look them up because I have not baked in 2 years. They come from my old handwritten cards. Hmmmm… we just moved. I wonder where those cards are?! Eek. Hope they are not lost! The buttercream I use either has custard in it (German?) or cream cheese or sour cream (Russian?).
Mmmmm… cake trimmings. 
Apparently, one Russian baker found a way to utilize these into a tasty treat called “the potato pastry.”
I’ve done cake balls out of trimmings (eg, when slicing off the top of a WASC, minus the crusty part.) Some conventional recipe where you mix in icing, form balls, then dip in chocolate. Big hit. The balls freeze well, without the chocolate. Too sweet for me. Now, this would be something to really dress up, maybe cross with a good chocolate truffle.
I’m familiar with cake balls, but I’m clutching my pearls at the idea of polluting a good chocolate truffle with that stuff.
No, just no!
@BunsenBurner , if you want to make great cakes and real buttercreams, but The Cake Bible by Rose Levy Beranbaum. Really. Honestly. It transfigured my cake baking.
“No, just no!” is right. Not to worry. No plans, not even research yet, and no intention to make crap. Lol.
It would be much higher concept than icing balls with cake shreds. I’m only envisioning the presentation at this point.
Ok, wait, I too thought maybe it was old-fashioned, thin cake pans. So I bought really good ones. Hmmm, that wasn’t it.
I sold my stove with my house. We’ll see if the next stove bakes better cakes. I’m still pretty sure it’s me, not the current stove
@Consolation, very funny - I didn’t even notice the cake in the photo.
I totally agree with using recipes from the Cake Bible. Rose Levy Beranbaum is amazing in her knowledge, precision, and quest for the perfect recipe. When I used to make 14 and 16" layer cakes, I always used her recipe and the magi-cake strips.
Here’s what she says about why cakes dome: