Roberts said she had originally visited the library after seeing a poster advertising an activity where children could decorate their own bags.
After discovering the swap shop, she said she was pleased to see so many families taking part.
She said she had already put aside a bag of unwanted costumes at home and welcomed the opportunity for other families to reuse them.
“There’s such a good sense of community here,” she said.
Roberts called for similar events to be held throughout the year, saying children also needed fancy dress outfits for school discos and other occasions.
She said she did not want children to feel left out because their families could not afford costumes.
