Here are 3 Christmas Tree designed to fit over a tealight or used plain just for decoration.  

The stl file is solid to be printed in vase mode to make the tree hollow.   Use 0 bottom and 0 top layers.  The use of a brim will be helpful to get the tree to stick to the print bed.  Trees are 75mm wide and 110 tall and can be scaled to meet your need.  One photo shows the tree scaled to 90mm and 130mm tall.  Print time is approximately 50 minutes for 1 tree.  

Nozzle size: 0.4 mm 

5mm or larger brim recommended
0.2mm layer height
0.6mm wall line width recommended 
50mm/sec print speed
Spiral Vase Mode enabled (spiralize outer contours in Cura)