Do you need a trim kit? If you get the 18" tall upper cabinet finished inside to match the outside, then you really don't need the trim kit. It will be less expensive in the long run and you won't have to worry about whether the old trim kit will fit the new MW when you have to replace it in the future (and you most likely will need to replace it, most MWs, especially countertop models, in my experience, don't last that long). [Our MW drawer has lasted almost 9 years, but none of my countertop models lasted more than 5 - they were more expensive countertop MWs b/c I wanted & used the various options but they still didn't last very long.]

I would also ask if the cabinet opening where you plan to put the MW can be "frameless" so you have a full-width opening.

Does your Kitchen Designer (or, if no KD, then cabinet salesperson) know what you're planning? If so, s/he should know how to order the cabinet. If not, tell him/her!

We did a countertop microwave above out wall oven and then put an appliance garage type of cabinet door to hide the microwave. This ended up actually being cheaper than the trim kit and I prefer the look.

Thank you Buehl. I definitely don't need the trim kit, I just thought it would add a finished look to the kitchen - which is open to the dining room and living room. I don't think I can order a frame-less option for that cabinet with the cabinet line that I am buying. I have found a few counter top microwaves that will definitely fit in the 16" depth and the clear width and height for the framed cabinet. Just wanted to see if there were any other options out there.

Thank you Lakeerieamber. I love your idea. Unfortunately I don't have an area that I can place the microwave in a 24" deep cabinet in my kitchen - trying to maximize my counter space.