I've done a few projects using variations on the faux batik method. I've tried it all- tempera, wax crayon but I think my favorite process uses oil pastels.
My Grade 10-12 mixed class had to choose a photo of architecture to draw. I encouraged them to choose a personal place- somewhere they've visited or would like to visit or a place with some sort of special meaning. They drew this onto heavy white 12 x 18" paper.
Then they outline all the pencil lines using coloured chalk.
Then they colour in the entire design using oil pastels making sure to not go over the chalk lines. It's best to stick to lighter colours. These need to be applied in a thick, opaque layer in order for the next step to work!
Then mix up some dark acrylic paint or India ink. Water down the acrylic paint to an ink-like consistency. Paint over the design and wipe/blot/dab off the excess with paper towels.
Some of my students work: