Opposed Double Spirals

Simple freehand ornament adapted to straight-nib pen

1    Simple semicircle
2    compound half- and quarter-circle curves

Repeat in reverse

1    Simple semicircle
2    compound semicircle and quarter curves

Now together, not too close

1    First half circle
2    Second, opposed half circle
3    Quarter circle added to first half
4    Quarter added to second curve

The path should be of uniform width