My 19 month old sounds a lot like yours, OP. She loves to scribble and will do it all day long with crayon, marker, pen, pencil. With the markers especially, she's very careful with the routine of picking each color, saying the name, drawing (sometimes circular scribbles, sometimes lines or slashes, sometimes wide sweeping strokes, sometimes very emphatic dots). After she's used each color she puts it back into the bunch of markers, but she does not use that color again until she's gone through all of the others.
With crayons, pencils etc. she holds them in the "correct" grip and prefers regular-sized. She doesn't like the fat ones and outright refuses to use the triangular or block style. I was a little perturbed at this at first because I made her some very lovely mixed color star-shaped crayons and she didn't want to try them at all. Maybe when she's a little older she'll branch out.
She always requests for us to draw her favorite animal, a kitty. Just last week she started doing her first deliberate labeled drawing when, after I drew the circle for the kitty's face and the ears, she took the marker from me, said "eyes," and scribbled in two little eyes. Now every time she asks us to draw a kitty, after we do the head and the ears, she takes over and makes eyes, nose, mouth and whiskers. The eyes usually are in the correct place for eyes and usually look like either little scribbled circles or arcs, the nose and mouth can vary, and the whiskers generally look like scribbly splotches on the side of the face.
She loves to paint with food-colored yogurt or tempera, but will only use a brush. She doesn't care much for using sidewalk chalk, as it's too fat for her to hold the way she likes and it gets her hands messy. She loves to "paint" the outside of the house and patio with water and a big brush.