On Thursday, May 28, 2020 at 5:57:37 PM UTC-5, Hawk wrote:

I think that will be the direction I go, but I still need to figure out
how to make a curved perimeter around the granite.

That's exactly what I've been saying all along. That's the problem, getting a perfect fit along the curved edges in/for a flush fit surface. It doesn't matter what support you have under the slab or the attachment method to the carcass.

Do you have the precision tools for either cutting the slab or cutting the wood frame so that their edges mate perfectly? If not, then you'll likely have small gaps, as I have, along the curved boundary. Otherwise, you'll need to take great care to hand rout, hand cut/carve and/or sand those edges for a perfect fit.... unless a perfect fit or a near perfect fit is not necessary. The sample pics/links you referenced seem to indicate perfect fit results.

Sonny