We did this, with a countertop microwave…it’s the largest mw GE offered 7+ years ago. Our contractor modified the shelf. There is enough air circulation behind, below, and on the sides of the unit:

That's looks like what I want. I read on one of the discussions here, that the microwave must be supported on 3 sides by walls. Yours is not. Mine is in a corner too. Is that a concern ?

I don’t see why it should be. The upper cabs are attached/supported by a wall. These cabinets are well built, and quite sturdy. I can pull on the shelf…it won’t budge. Been almost 8 years (come early February), with no issues. You just need a really good contractor. Mine did an excellent job of modifying the shelf cubicle. If you look closely, you’ll see it.

Of course, your cabinets are much older, and are not full overlay. Notice how you can see the frames in between the doors of your cabinets, but you can’t see the frames on mine. What you have is partial overlay. I don’t know, but that could make a difference in creating a shelf like I have.

@darbuka, Check out this discussion on Houzz reg the placement. I am glad to know that you had no problems with corner placement.

https://www.houzz.com/discussions/4630116/question-on-microwave-cabinet-placement

The cabs mentioned in your link are Cliq Studios, which is Chinese import junk. Search for other threads on Cliq.

I would in no way compare Cliq cabinets to what I have, a custom line from Tedd Wood…made in PA, and having a lifetime warranty. As the thread you linked to indicated, there’s no reason a mw placed in an upper shelf at the end of a cabinet run, cannot be placed there…as long as the cabinet is sturdy, and screwed into the back wall.

Again, your cabs are quite old, and are partial overlay. I have no idea of their quality, and whether they are sturdy enough to achieve what you want. Between the quality of my cabs, and my experienced, excellent contractor, I had no qualms about putting the mw there. Nearly 8 years later, no issues.

@S M, the difference is, your “end of a cabinet run” butts up to a wall, which is what the OP is suggesting is needed. Mine, is not. My end run of cabinets has cabinet ends. It is not against a wall.

Ours is on a shelf. The microwave is small and cheap. Does what we need it to do.

@darbuka, absolutely right. Coffee hadn’t kicked in 😜

Thanks all for your comments. Your suggestions duly noted and appreciated