This is recursive Openscad code to generate Gosper curves of any order desired.  By invoking gosper_f(order, x1, y1, x2, y2); it will create a Gosper curve of the desired order starting at (x1, y1) and ending at (x2, y2).  You can play around with the “line” routine to make the walls whatever thickness you desire for 3D printing purposes.  As the code starts out, it will create an order 4 snowflake that is 6mm high with 2mm thick walls.