Bauble

Added a rectangle with fill none to show off the boundary Helpful to have (0, 0) as centre of image

Tree

Had to increase the viewBox height to include the supplied coordinates

Bauble with decoration

This looks easy. Define a circle as the clipPath in <defs> then use clip-path in the polyline

snowflake

define one arm of the snowflake in defs then use that definition with rotation every 60 degrees