I’ve made a texture pack for use with the G’MIC Artistic Stylize filter.
They are available on my Gumroad shop here: Handmade textures for use with G’MIC
The textures include seamless PNG. images for charcoal, pastel, pencil, conte, colouring and carbon pencil and watercolour. One of these sets (pencil, charcoal and pastel) will be included in the next update for G’MIC.
I made them from scanning handmade tonal studies into my computer and then turning them into seamless patterns. Here are some of the source images for the curious who may want to create their own textures: