Some vector drawing tools. Fountain Pen tool. Allows exporting the drawings to SVG format which can be imported easily with more complex vector design programs like for example adobe Illustrator.
Define each curve with 2 control points and an origin and end point, dragging your finger on the screen.
With the use of a pointer, the precission you can reach drawing with the finger is similar to drawing with a mouse.
SVG import (except the ones created with this app) isn't supported.