Proportion let you build 2D planar geometric figures in JavaScript. 
I like geometric constructions. Drafting also is cool. 
Tile patterns: cool. 

Cloning the repo and loading index.html in a browser allows viewing of
all content; I also have it online at workly.com/proportion.

The code in proportion.js is heavily commented. 
The HTML pages in the "examples" directory are a tutorial.
The code in "prMachines.js" is a set of connom geometric constructions. 

Next up is testing/debugging/refinement of lofting.

Neal McDonald
Jan 2, 2017