Can I put a counter top microwave under the counter?

As long as it vents out through the front, it shouldn't be an issue, good luck!

Wow... had not thought of that🤗

I have done that with mine. You need to make sure you have several inches of open space on all sides, including the back. Once in a while, the microwave will overheat and just stop, due to the built in sensor to prevent overheating/fires. This usually happens when I have set the microwave for five minutes or more. As you can see in the photo, I added a shelf with wood to the bottom of the cubby so that I could slide the microwave a few inches further out, to prevent overheating, when I am microwaving for a longer period of time. Also I open the door of the cabinet on the left of the microwave, to allow more airflow to the back of the microwave. There is no wall between that small cabinet and the microwave so more air can flow. Just make sure your microwave has an overheating sensor that will automatically shut it down. I would imagine that all newer microwaves do have that. Since you are building from scratch, it shouldn'tbe a problem. I had to work with an existing cabinet over the stove.

You need to watch out for the vents. Mine has large vents on both sides. Leave plenty of room around the microwave. This will also be a help if/when you need to replace it--you won't have to find a microwave of the exact same dimensions.

Great ideas! Thank you.