Any help would be appreciated...

Looking to replace a built in microwave with associated trim kit. Both microwave model and trim kit model are no longer made.

All the trim kits that I can find online have very specific opening dimensions. None of these trim kits match my existing opening.

Is there a way to enter my opening dimensions and match any and all trim kits that are available?

Once I get a trim kit that fits, I can match it to a microwave.

This has been a very frustrating honey do item!

is it feasible/difficult to change the opening size

The trim kits I find are too small for my opening. If it were the other way around, I could cut it larger.

could you frame the size opening you want and cover the gap with sheet rock

I had to increase the opening at the top. I was then able to install the GE Advantium oven/microwave without a trim kit.

An appliance specialist will be able to look it up