I can't imagine why I couldn't find this earlier...

Anyway, here it is.

https://www.legacy.com/us/obituaries/nytimes/name/peter-lippman-obituary?id=38299616

LIPPMAN--Peter J. Children's book author and illustrator, on November 9, 2022 at age 86. His many friends will remember his deeply inquisitive mind, his sense of humor, contagious laugh and love of the outdoors. Lippman grew up in New York City and split his time between the city and his home in Roxbury, NY in the Catskill Mountains. Taking advantage of the natural wonders the Catskills offer, Lippman was a white water kayaker, a skier, and an avid bird-watcher and hiker. He attended Columbia University, where he received Bachelor and Master degrees in Architecture. While embarking on what was to become a successful career as a graphics artist, his illustrations began to appear in and on the covers of a large number of magazines and newspapers including Holiday, The Saturday Evening Post, Publishers Weekly, Harper's and The New York Times. At that time he also became involved in the world of children's books both as a writer and as an lllustrator. His first book, Plunkety Plunk, was selected by The New York Times as one of the best illustrated children's books of the year. More than fifty of his books have been published since then, including the classic The Great Escape or The Sewer Story. In the 1990's, he invented and was granted a patent for a new three-dimensional format where the book, when closed, is a free-standing sculpture in the shape of a building such as a castle or barn, and when open is a board book. It is the basis of a line of 14 titles in the Mini-House and Mini- Wheels series designed and illustrated by Lippman and published by Workman Publishing. Still in print after more than twenty years since the advent of the first Mini-House book, they have sold more than three million copies. At the same time that Lippman was engaged in magazine illustration and children's books, he created numerous paintings and sculptures which he showed occasionally at New York galleries. An artist who worked primarily in water colors and later in acrylics, he also utilized other diverse materials such as bronze and Styrofoam. He was still actively working and creating until the time of his death. He is survived by his wife of many years, Anne Phalon, and his cat, Terrance, as well as myriads of loving cousins and friends. A remembrance of his life will be announced at a later date.
Published by New York Times on Dec. 4, 2022.
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About "The Great Sewer Escape" (1973):

Valerie: "This was my favorite book as a child. Silas, a young alligator kidnapped from the swamps of Florida is sold to a family of tourists who bring him back to their hometown - New York city. Unfortunately, when he starts to get too big for their apartment, they do what any family would - flush him down the toilet. In the underground world of the sewer, he meets other alligators who share his fate, and they plot and execute their escape together.

"This book is out of print, but I'd be willing to sell my battered copy for $1,000,000."

About "Plunkety Plunk," from Google Books:

"Once upon a time there was a blacksmith who loved wrought iron more than anything else in the world. His wife loved wrought iron, too, and so did his son Stanley, who was about your age. Stanley and his mother and father were all very happy until one day the blacksmith discovered that his neighbor was making iron faster than he could. The neighbor had bought an automatic furnace machine. Since the blacksmith strongly felt that hand-wrought iron was the only iron for him, he was very unhappy, and, being nervous and upset, he accidentally locked himself in a large birdcage he was making for the town zoo. But Stanley and his friends---the armadillo, the lion, and Oscar the dinosaur--found a way to get the blacksmith out, and even solved the problem of the neighbor's furnace machine in such a way that the blacksmith could once more sing, 'Smash, crash, Plunkety-Plunk! Hand-wrought iron is the only iron for me!' "

https://www.etsy.com/uk/listing/775870429/1963-plunkety-plunk-peter-lippman-ariel?show_sold_out_detail=1&ref=nla_listing_details
(pictures from the book, plus a 1963 photo of Lippman)
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What I posted in 2016:

Not to be confused with the photographer Peter Lippmann (note the extra "n").

His preschool board books include the Mini House Book series.

https://www.google.com/search?q=books+%22peter+j+lippman%22&tbm=isch&ved=2ahUKEwiaj5mu3JSEAxVmAWIAHZkDBeQQ2-cCegQIABAA&oq=books+%22peter+j+lippman%22&gs_lp=EgNpbWciF2Jvb2tzICJwZXRlciBqIGxpcHBtYW4iSII5UABYtTZwAHgAkAEAmAFDoAGoBqoBAjE1uAEDyAEA-AEBigILZ3dzLXdpei1pbWfCAgYQABgHGB7CAggQABgFGAcYHsICCBAAGAgYBxgewgIGEAAYCBgeiAYB&sclient=img&ei=chrBZZqOAeaCiLMPmYeUoA4&bih=900&biw=1280&hl=en
(book covers, including the Mini House books)

https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1280&bih=900&q=+%22Science+Experiments+You+Can+Eat%22+lippman&oq=+%22Science+Experiments+You+Can+Eat%22+lippman&gs_l=img.3...909.5597.0..5821.13.6.1.6.0.0.136.754.0j6.6.0....0...1ac.1.64.img..0.4.397...0i30j0i24..4tA_jES0m9I#hl=en&tbm=isch&q=%22peter+j+lippman%22+books
(cover of "Science Experiments You Can Eat")

https://www.google.com/search?q=%22know+it+alls%22+peter+books&hl=en&biw=1280&bih=900&site=imghp&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj2h82KtufMAhUFNhoKHYn_BZ4Q_AUIBygB
("Know It Alls" book covers - with alligators)
From a 2001 Catskills article I can't find anymore:

Lippman described one of the Mini House books: "When it's closed you have this little building. Then, you open a flap and it's a book. Think of a loaf of bread, with each slice being a page. Then, think of a barn, with a cupola on top, being put through a bread slicer."

From "Contemporary Authors":

"Contributor of articles on the history of architecture to periodicals, and of illustrations to magazines, including New Yorker, Town and Country, National Wildlife, Harper's, and Reader's Digest."

WRITINGS BY THE AUTHOR:

SELF-ILLUSTRATED JUVENILES
•Plunkety Plunk, Ariel Books, 1963.
•New at the Zoo, Harper, 1969.
•The Little Riddle Book, Harper, 1972.
•Busy Wheels, Random House, 1973.
•The Great Escape: or, The Sewer Story, Golden Press, 1973.
•Ingrid Our Turtle, Golden Press, 1973.
•The Mix or Match Storybook: 2, 097, 152 Silly Stories, Random House, 1974.
•Archibald; or, I Was Very Shy, Windmill Books, 1975.
•From Here to There, Bookstore Press, 1975.
•Animals! Animals!, Golden Press, 1976.
•Busy Boats, Random House, 1977.
•Peter Lippman's One and Only Wacky Wordbook, Golden Press, 1979.
•Peter Lippman's Great Mix or Match Book, Random House, 1980.
•Busy Trains, Random House, 1981.
•Mix or Match Mysteries: Carstairs Cat Solves Millions of Cases, Random House, 1982.
•Trucks, Trucks, Trucks, Doubleday, 1984.
•Peter Lippman's America, Crown, 1985.
•Peter Lippman's Opposites, Grosset &; Dunlap, 1988.
•Peter Lippman's Numbers, Grosset &; Dunlap, 1988.
•Old MacDonald's Barn, Workman, 1993.
•Santa's Workshop, Workman, 1993.
•3 Pigs Garage, Workman, 1998.
•Space Station, Workman, 1999.

ILLUSTRATOR; JUVENILES
•George Selden (pseudonym of George Selden Thompson), Sparrow Socks, Harper, 1965.
•Selden, Oscar Lobster's Fair Exchange, Harper, 1966.
•Selden, The Dunkard, Harper, 1968.
•Bill Martin, Jr., The Haunted House, Holt, 1970.
•Vicki Cobb, Science Experiments You Can Eat, Lippincott, 1972.
•Cobb, Arts and Crafts You Can Eat, Lippincott, 1974.
•Supersuits, Lippincott, 1975.
•Noodles, This Little Thing, Holt, 1979.
•Jovial Bob Stine, The Pigs' Book of World Records, Random House, 1980.
•Stine, Gnasty Gnomes, Random House, 1981.
•John Archambault, Allafred the Anteater, DLM Teaching Resources, 1987.
•Martin and Archambault, The Bugs, the Goats, and the Little Pink Pigs, DLM Teaching Resources, 1987.

"THE KNOW-IT-ALLS" SERIES; PUBLISHED BY RANDOM HOUSE
•The Know-It-Alls Help Out, 1982.
•The Know-It-Alls Take a Winter Vacation, 1982.
•The Know-It-Alls Mind the Store, 1982.
•The Know-It-Alls Go to Sea, 1982.