BlocksCAD Snowflake Activity & Challenge

[BlocksCAD](https://www.blockscad3d.com/) is an official [Hour of Code^TM](http://hourofcode.com) Activity. BlocksCAD is a free online software designed to teach students coding and Computer Aided Design. During this Challenge, students will use BlocksCAD to create a 3D design for a snowflake by writing a program to rotate a shape around an axis (using a loop).