I'd do T shape. where the chair is you would instead have more cabinet underneath and extend the top toward the chair and 3 on a side facing each other. I might do it table height . I guess w these adjustments if you just scrap the base you have and get it the right height/right length and 15 in overhang is enough. Moving in a different direction you could search out or have a woodworker build you a trestle table or country farm table type piece.....butted to the working part of island which is commonly done for an unfiitted look. Is your top material all purchased?

Certainly you have metalworkers in your area that can fabricate a solution. I prefer a frame made from 1” square hollow rod…

Hallett, what would the frame be attached to? My wife doesn't want any corbels or floor support, we just want to support the overhang.

(including hospital bills)

I am a fabricator. You need a fabricator with experience with large overhangs particularly with a fissure prone stone like quartzite. As Joe mentioned you need a substantial structure to anchor the cantilever supports which would have to be integrated into the cabinet. If you were my customer I would advocate a couple of posts and associated support elements set back far enough from the edge that you would never contact them sitting at the table. Much simpler, doesn't require a very special cabinet, and safer to boot since it takes less skill to execute properly.

I'd square off the corners and use a simple leg post. I'd also drop the level to tabletop level instead of countertop if this is your main dining area.

The other posters have talked about structure. I am going to call out the design of this creation. The round top could have worked visually. This rectangular top is just a folly visually that will be compounded when all the barstools are added.

Eating at countertop height gets old very quickly.

I’m not an expert but that looks like an accident waiting to happen.

Don't abandon your idea. Check out kitchens by British designer by Johnny Grey for really interesting and innovative ideas on supporting counters and on kitchen design in general.

https://www.johnnygrey.com/

Starnold, thanks for the encouragement. I think I just need to find the right team.

John:

You need to be able to walk across whatever substrate you build. The countertop is just veneer.

20 pounds per square foot. That is how much weight you expect that little cabinet to support.

A black metal base could visually disappear beneath a trestle table set at a right angle to the actual kitchen cabinet island :

https://www.etsy.com/listing/747073089/dining-table-table-table-base-handmade?gpla=1&gao=1&&utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_ps-a-home_and_living-furniture-dining_room_furniture-kitchen_and_dining_tables&utm_custom1=k_CjwKCAjw3_KIBhA2EiwAaAAliirEkCMc3Ew57ivHEz4Zovg9xaqr8bqYF01DmQUypN-7wb4wrvUKlxoCRm8QAvD_BwE_k&utm_content=go_12567673668_122422047751_507253697197_pla-305291086702_c__747073089_112984025&utm_custom2=12567673668&gclid=CjwKCAjw3_KIBhA2EiwAaAAliirEkCMc3Ew57ivHEz4Zovg9xaqr8bqYF01DmQUypN-7wb4wrvUKlxoCRm8QAvD_BwE

If your 18" x 36" cabinet is expected to hold around 20lbs per sq ft, it should be able to withstand around 90 lbs of continual weight.

you are talking about putting 450 pound slab on something made to withstand less than 1/4 of that weight!

it is not just about figuring how it could be done, you should ask, should it be done. We are talking about weight dispersment here. all engineers use this principal when considering load on structures and even roads. the weight you put on top disperse down below to your cabinet, then the floor, then the floor joists and down from there.

you must properly support the load and a 18 x 36 cabinet will not support the weight even if you find steel supports!

Can your floor handle the weight of all that quartzite without reinforcement from below? You also have not considered how the larger dining portion cuts into your traffic aisles, don't forget you have to add chairs! The rectangle w/ angled corners is a weird addition to a perfectly fine island. The (outdated) angled corners are what people want to take out of their islands to update them. Obviously, that small of a cabinet cannot hold that large of a piece of quartzite safely and this should have all been designed before it was built not after the fact. Might be more cost effective to buy a new dining table and chairs and forget about adding it to the island at this point.

Maybe I'm not looking at the right pictures, but all the island tops and large overhung countertops I viewed on the johnnygrey site have some sort of leg or large corbel support.

I need to understand the reason for this design at all. IMO 15" overhangs are more than enough and I also think that island is just plain too big and poorly planned

With all that space why not have 2 smaller islands, one for seating and one for kitchen prep?

You are making life too difficult. Just buy a nice table and be done. The hoops you will have to jump through for a table design that does not seem to have a defined purpose will be a lot and expensive and have a dubious outcome. Why would you want to put yourself through this?

And BTW, the sole cheerleader on this thread, that you were happy to hear from, took the opportunity to write his comment in order to provide the link to his UK firm. So that is spam, and therefore, it is in his interest to say what you wanted to hear. Not advice that I would take or give credence to.

"And BTW, the sole cheerleader on this thread, that you were happy to hear from, took the opportunity to write his comment in order to provide the link to his UK firm. So that is spam, and therefore, it is in his interest to say what you wanted to hear. Not advice that I would take or give credence to."

M Miller:

It isn't spam when the poster is offering a good faith solution. It is spam when you start a thread to promote yourself directly. The fact that he's in that particular business is irrelevant. Your argument is the logical fallacy of relevance, ad hominem circumstantial.

@Joseph Corlett, LLC - that’s a lot of petulance you got there. Life is too short. I do not know why lately you have been coming to spammers’ defense. Not only here, but on other threads. You’ve talked on other threads something about spam costing you money on Houzz, or Houzz taking advantage or something you were saying about spamming with resentment—I admit I don’t remember—just seems spamming is on your mind heavily. I am not going to engage further with you on this.