What is your hardware projection? Will you install a hinge limiter?

I haven't chosen hardware yet...but as long as the 15" door opens, I wouldn't mind if the 15" door handles hit the 18" cabinet.

What's a hinge limiter, a hinge that limits how wide the door opens?

So, you plan to use 24" and 15" cabs to create 9" of space in the blind? Are you doing it because you really need the space? I planned to do one with my IKEA build but my carpenter husband talked me out of it as it required a 3/4" panel to drill the hinge holes into and special hinges. The extra work wasn't worth it to me because I really did not need the space. Here is what I ended up with.

I collected info from Ikea Fans that may be useful to you. Here is how one person did hers.

Here is a link that might be useful: Dalbrough's Ikea Hack

Thanks for posting those pics!

I didn't realize how complicated it would be to build a blind corner cabinet. No, I don't exactly have a need for the extra space. Maybe I will do what you did.

How much filler did you use in that corner? I have enough room for 2" of filler next to the 18" cabinet, but I have less than an inch on the other side.

I have 5 1/4 on the left and 7/8 on the right. It's not perfect, but it functions fine.

Do you think it will work if I only use 1/4" or 3/8" filler on the side with the 30" cabinet? I'm worried that I won't be able to open the door.

The 18" door on the left is 3/4" thick so you really need at least 3/4" to fully open the door, but you will still be limited by your door hardware. Unless hinge limiters are used there is always the chance of the doors bumping in a corner.

What you want to do is absolutely possible with an Ikea system and I personally would choose the 30" over 2 smaller cabs. I never slam doors and you don't really need it to fully open. As you can see in this picture, the knob prevents a full 90 degrees, but I've never seen it as an issue. There will be no clearance issues at the hinge as the left side of the door moves a 1/2" to the right as the door opens.