In addition to painting, Appel also wrote children's stories, complete with illustrations. One, "The Story of Juliet" (1945), appears in her papers housed at the Smithsonian's Archives of American Art. Appel designed a war memorial for the Woodstock, New York community village green. Her project was unanimously accepted by the War Memorial Committee and it was to be installed for a commemoration of Pearl Harbor Day on December 7, 1947. Austin Mecklem died on October 7, 1951, after a lengthy illness. For two years after his death, Appel continued living in Woodstock and helped plan a memorial exhibit for his works. In 1953, the artist's community hosted a retrospective memorial to Mecklem and Jeanne Magafan, another member of the community who had recently died. After the memorial show closed, Appel and her two daughters, Merrill Mecklem and Sarah Greer Mecklem, moved to New York City, where she began work as an illustrator of children's books. She also worked as a puppeteer with Bil Baird and wrote a second juvenile fiction story called "Perlydew". In 1960, Appel married Carl Harms, who was an executive with Actors' Equity, as well as an actor and puppeteer. After her marriage, Appel changed her professional name to Marianne Harms. Soon, she went to work for Jim Henson and became one of the designers of The Muppets. She was known for creating some of the more intricate Muppet characters. In 1975, Harms designed costumes for the pilot "" and in 1977 she worked on "Emmet Otter's Jug-Band Christmas" as one of the puppet creators. Harms and several other artists created the Nativity Muppets for the 1979 television special "" and her design work on the special was nominated with other contributors for an Emmy Award for "Outstanding Individual Achievement in Creative or Technical Crafts" in 1980. That same year, she served on the design team for the series 5 episode of "The Muppet Show" hosted by Loretta Swit. She served on the team of designers that created the Podlings in "The Dark Crystal" in 1982 and then the following year worked on "Fraggle Rock" fabricating designs for the episode "Preachification of Convincing John". Harms died on September 26, 1988, in New York City.