Icosahedron Puzzle Lamp Shade (III) Fractal

Icosahedron Puzzle Lamp Shade (III) Fractal
Print 20 pieces and put them together.
https://en.wikipedia.org/wiki/File:Icosahedron.gif
After assembly, the diameter of the lamp shade will be
Large version: ~ 21 cm
Medium version: ~17cm
Small version: ~13 cm

Recommended settings:
In stead of commonly used PLA filaments, use Nylon or ABS filaments for higher toughness and resistance to the heat from the lamp.
For Large and Medium versions: Layer height 0.2 mm
For Small version: Layer height 0.15 mm
For all versions: At least 5 perimeter loops to enhance the shear strength

Updated 2016/09/30
The STL files are modified to have larger tolerances at the vertices for those who feel difficult during assembly.

Similar things:
Icosahedron Puzzle Lamp shade (I) Dahlia http://www.thingiverse.com/thing:1782444
Icosahedron Puzzle Lamp shade (II) Heart Shape Petals http://www.thingiverse.com/thing:1786301
Deltoidal Icositetrahedron Puzzle Lamp Shade - Clover http://www.thingiverse.com/thing:1793174