End Caps of TubeGeometry

Do you mean something like that? (example 0.4 * Math.sin( Math.PI * 2 * v ))

You can do things like that with my addon THREEf. Addon. Produces almost infinite many time-varying geometries with functions

hofk (Klaus Hoffmeister) · GitHub

examples https://hofk.de/main/threejs/sandboxthreef/examplesTHREEf%20r90.html

https://hofk.de/main/threejs/sandboxthreef/formLibrary.html
e.g.

//0011 curved cylinder  @author hofk 
 withBottom:	true,
 moveX:		function ( u, v, t ) { return Math.exp( -200 * v * v * v * v ) }

curved%20_cylinder