If you wanted a specific cabinet size

Sounds pretty simple and straightforward. Build it.

If you don’t think you can do it, call a cabinetmaker.

If you decide to build it yourself, use plywood for the carcass and the type depends on how you will want to finish it.

For the door frames I suggest using poplar since it really stays straight and is not as expensive as other more exotic hardwoods. I've had perfectly straight 1 x 6 pieces of cypress, oak, mahogany, etc. take a bow once run through the table saw cutting them down to size for building cabinet doors.

If you're buying doors I would start there. Might be able to find some doors close to the size you need. Custom sizes will cost a lot more. Find that then build cabinet to fit the doors.

I'm in the same boat as the OP.

Any cabinet maker recs in BR area that would do this small of a job?