New from Martha Stewart – the sibling rivalry collection, in envy green and raging red.

The domestic diva’s estranged younger brother, Frank Kostyra, plans to begin selling on eBay today mementos from Stewart’s childhood, right down to her dried chewing gum.

The auction is expected to infuriate Stewart, who has a hard enough time selling her own products in the wake of her conviction last month for conspiracy, obstructing justice and lying to the feds.

But the black-sheep brother offers no apologies.

“Why do I need her blessing? These are my items,” he told The Post.

Asked what he’ll do with the money, Kostyra replied, “I’m looking at charities – though, of course, charity begins at home.”

Most of the furniture and kitchen appliances are from the former family home in Nutley, N.J., where the six Kostyra children grew up.

When their mother moved out of the house in 1987, Frank Kostyra, a self-described “pack rat,” put hundreds of items in storage.

Now living near Mobile, Ala., running a small cable-television shop, he hopes to rake in a tidy sum from his trove.

“I expect some items will go phenomenally high,” Kostyra, 59, said.

Titling the relics “Martha Stewart Heritage Authentic Childhood Collection,” Kostyra has paired the mementos with magazine columns Stewart wrote in which they were mentioned.

For instance, in December 1995, a piece in Martha Stewart Living reminisced about melting chocolate in her family’s double-boiler.

Also up for sale: An off-shoot of the family’s fig tree, and the “vehicle which helped launch her to stardom,” a 1976 Chevrolet Suburban that Stewart used to start her catering career.

Kostyra expects to post up to 60 more items, including the pink Formica kitchen table at which Stewart announced her engagement.

It comes “complete with her chewing gum and drawings still visible on the underside,” Kostyra boasts.

Some items are intimate and personal, including the black Singer sewing machine on which Stewart made her 1961 wedding dress and a 1950s Kitchen Aid mixer which she once described as her mother’s “prized possession.”

Others are weirdly random, including a sledgehammer Stewart used to expand a kitchen, and the key to a pair of her roller skates.

Kostyra said the bric-a-brac tells the history of Martha, illustrating a childhood spent in pursuit of good things. For instance, their father, Edward, would line up the kids to make sausages, while his mother, Martha Sr., taught them all to sew. The kids learned “from two parents who devoted their time to teaching and used us as guinea pigs,” he said.

No one has appraised the pieces, though Kostyra thinks fans will be excited to own a piece of the perfect homemaker’s childhood.

But he rejects the notion that he’s trying to capitalize on his sister’s troubles.

“People say I’m obsessed with Martha, but that’s not the case,” Kostyra said. “I have these things. Why not share them with the world?”

Stewart, 62, is unlikely to see it the same way, as relations between the two have always been tense.

Interviewed after her trial last month, Kostyra told The Post, “Martha and I have always had a lot of sibling rivalry – I remember us lying on the floor biting and scratching as kids, trying to get each other to say uncle, but she would never give in.”

The two have barely spoken in five years, and Kostyra has said that Stewart falsely accuses him of cooperating with a tabloid magazine in a negative piece about her. He refused to elaborate, however.

“These are things that I probably better not speak of,” he said. “Love covers a multiple of sins.”

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THE MARTHA COLLECTION

Frank Kostyra – Martha’s black sheep brother – describes the items going up for auction on eBay:

* “The black Singer sewing machine on which Martha and her siblings learned to sew, and on which Martha made many of her garments including her wedding dress for her 1961 marriage.”

* “We have Martha’s entire childhood dining room suite plus the lace table cloths on which the priest blessed the Easter dinner for Martha’s family.”

* “Martha Stewart’s childhood, 55-year old, aluminum Double Boiler in which she learned to melt chocolate and in which she made her many flavored frostings and puddings, even duplicating her mother’s famous penuche and confections.”

* “Martha’s favorite bent-oak childhood rocking chair, which resided in her grandparent’s oak-furbished guest bedroom. Martha and her siblings would rock for hours when they visited their grandparents.”

* “Martha’s 5-foot Sewing Form which she used to form fit and base stitch her many garments, including her wedding dress.”

* “A green Chevrolet Suburban . . . Stewart’s first work vehicle, which helped launch her to stardom, and in which it all began back in 1976. (The) catering activity eventually launched her into her mega celebrity status.”

* “We have Martha’s 1953 Sears Roebuck fur catalogue, which she used to trap and sell furs with her brothers.”