Marvin was among dozens of private sutlers - business operators who sell period clothing, weapons and crafts - who came to the fort as part of the event. Park volunteers and workers also dressed in 18th century clothing styles, giving oral and visual history lessons to those who were interested.
Steve Robinson, the park historian, said between 4,000 and 6,000 people usually come to the event.
Robinson said the weekend focuses on the time between the 1730s and 1790s and celebrates the French and Indian War period. Fort Frederick itself is a war relic, built in 1756 by the Maryland colonial government to defend frontier settlements against native attacks and supply attacks against the French.
Sonji Stanton, 36, was looking over the pelts in Marvin's tent Friday as her daughter and some classmates perused the rustic items.
"It's worthwhile," Stanton said. She said her daughter was on a field trip with classmates from Whittier Elementary School in Frederick, Md.
"A lot of things we take for granted," Stanton said.
Her daughter, however, had a different take on the pelt shop.
"They're dead animals. Can we leave? I don't like the smell," said India Jones, 9.
Other state park workers were at the event Friday to build both personal and work collections.
Jeremiah Hornbaker, 26, works at South Mountain State Park. He said he works there as a Civil War historic interpreter, among other duties, but is hoping to brush up on enough history to do colonial-era work.
"It's like a mental overload, just kind of learning the differences" between clothing and weapon styles from one year to the next, Hornbaker said. "I haven't really studied this, so I'm kind of getting my feet into it."
Inside the fort walls, volunteers dressed in military clothing marched and fired rifles as they may have more 200 years ago.
Jim Rogers, 33, of Savage, Md., portrayed a drummer and was wearing a wool coat, stockings and knickers as the heat crept up.
"If it's a really hot day, your shirt will get soaked," Rogers said. "They didn't run marathons in these things."
But the heat is part of living history, he said.
"It's a great way to learn the history. ... You understand it more personally than if you read it in a textbook," Rogers said.