THREEp finished
About a year ago, I started 
with the geometry generated by functions.
That was a first result.
With still well under 1000 lines 
of code.
Now also the addon THREEp is finished. 
Also some examples and a form library are now available on my site http://sandbox.threejs.hofk.de/ and GitHub hofk (Klaus Hoffmeister) · GitHub.
The library is still under construction.
form library THREEp.js
However, I have refrained from removing the seams on Geometry. The effort is disproportionately high. Especially since Geometry has no long-term future.
For THREEf there is a further tool 
at
Modify indexed BufferGeometry (mouse or input) available.