Check my other slinky model: Slinky snowman
Proper print parameters are crucial. It is recommended to use provided Designer's print profile!
0.15 mm layer height, 0.97 flow rate, 90 mm outer wall/inner wall/internal solid infill speed, lot of cooling. Use modifier to add more weight to the base (for example use more perimeters for first 3 mm). Ignore warning about “floating cantilever”. PLA works fine.
Use sharp knife or spatula to separate individual layers of spring apart. Be careful not to cut yourself. Glue in star.