The wedding cake is nearly 5 feet tall.
The guest list is more than 1,200 people.
Pop star Natasha Bedingfield plans a celebratory video message.
And it's all free.
Planned in just under a month's time, the no-fee mass same-sex wedding Tuesday at Carlyle on the Green at Bethpage State Park will be as massive as it is historic.
As of Friday, 98 couples had signed up to be married and 1,206 guests had registered.
"For Long Island, it's going to be something else," said Steven Carl, owner of Carlyle on the Green. "Having this . . . is monumental."
The Long Island GLBT Services Network and area vendors have pulled together to put on a grand wedding and party.
At first it was going to be a simple wedding, but then things began to happen. Vendors recruited other vendors and used connections.
All are donating their services, including Carlyle, where events typically cost $135 to $200 a head. "Not everything is about what you get," Carl said. "It's about giving back."
The event has all the trappings of a one-couple wedding.
A processional, music, flowers, toasts and dances are part of the plan. So, too, is an open bar (beer, wine, soda and Champagne) and Gatsby-style food stations.
The cake will be no less than 12 tiers, requiring at least 150 pounds of sugar, 75 pounds of flour and too-many-to-count dozens of eggs, said Jason Ellis, owner of Top Tiers by Jason Ellis in Farmingdale.
"There's a little bit of stress," he said, "just a little stress."
Take, for instance, making a cake big enough to let every couple cut a slice.
Ellis thinks he has that problem solved. The bottom tier of the cake consists of separate rounded cakes, like petals from a flower, topped with tiers connecting them. It should provide ample cutting space, said Ellis, who estimated the cake's retail cost at $15,000 to $20,000.
And now to the vows.
Rev. Beverly Boyarsky has spent the better part of the last week agonizing over that.
"My heart is full," she said. "I want to say the right thing."
Boyarsky, of North Babylon, runs the Beacon of Light Outreach Ministry, and will conduct a civil ceremony, not religious.
She's still refining her words, but the ending is all set, and gender-neutral: "I'm going to pronounce them united in love."
The Guinness Book of World Records does not have a record category for the largest same-sex wedding ceremony, but it does have other wedding records:
Most couples married in 24 hours in a single location: 163 couples in Singapore on Sept. 20, 2009.
Most wedding guests: More than 150,000 people witnessed a Hindu Vedic wedding in India on Sept. 7, 1995, between the foster son of a chief minister and the granddaughter of a movie star.
Largest mass wedding ceremony in a prison: 120 inmates of a prison in Sao Paulo, Brazil, married their fiancees in a mass ceremony on June 14, 2000.
Most couples married simultaneously, multiple locations: 35,000 couples married by Sun Myung Moon in Seoul, South Korea, Aug. 25, 1995. Another 325,000 couples around the world took part via satellite link.
Source: Guinness Book of World Records