The popularity of adult crafting has helped drive sales of office supplies such as chalk, coloring pages and more.

As adults experience nostalgia over crayons and paints, adult crafting and the handmade movement are driving up art and coloring supply sales, according to The NPD Group’s Office Supplies Industry report.

The report found that coloring and art supplies are a more than $1.1 billion market, with in-store and online sales growing more than $75 million combined in 2015. The recent growth of the industry is being driven by new trends in adult crafting, as well as the sales of art and craft paper, paint and painting supplies.

Within the art and craft category, coloring pages–which includes adult coloring books–is the largest segment, based on dollar volume, and saw the largest store dollar growth last year. Meanwhile, drawing paper and coloring pages accounted for more than one-third of online growth within the category.

A host of artists and brands including Vogue, Highlights, Debra Valencia, Valerie McKeehan (of Lily & Val) and more are capitalized on the craze and have released their own coloring books for adults.

With the adult coloring trend’s continued growth, sales of complementary products like colored pencils, gel pens, painting accessories and acrylic paint are also driving growth within their respective categories.

Additionally, chalk and chalkboard usage is influencing sales as these items are now being used in businesses, home offices and as home décor. The chalk category also saw the largest in-store dollar sales increase last year, surpassing crayons in 2015. Meanwhile, both dollar and unit sales for chalkboards more than doubled in 2015 compared to the previous year.

“Social activities like paint nights continue to grow in participation in the U.S. and worldwide, providing the average consumer with fun and entertainment, and a chance to make new connections. The social and digital aspects of this movement have also opened the door for more consumers to build, maintain, and grow a small business,” says Leen Nsouli, director and office supplies industry analyst, The NPD Group. “The adult coloring books phenomenon is indicative of consumers’ need to sit back, relax, and focus on something creative also providing ‘me-time.’ Adult coloring has gained so much popularity worldwide that colored pencil manufacturers are challenged to keep up with the growing global demand.”