After some rework of a previous script (http://www.grasshopper3d.com/forum/topics/smooth-junction-blend-a-minimum-of-4-extrusions) to make node, here is a component to create node to join struts. It generates surfaces which blend sections of struts . 

22/12/2015:  Please consider it as WIP. Comments are welcome. As I have more comments when it works, it is also good to know if by chance it works for some people . Please unblock if it didn't work. Install it through Grasshopper (just put gha on the canvas ans GH will place it at the good place). 

v0.1

v0.2 (22/12/2015)

Inputs

 In order to work, this component needs 2 main things (underlined) : 

1) Lines => lines (not generic curves) create the network, the intersection of lines are the position of the node. You must remove duplicates lines. I didn't put the option in the component. Some good components exist to do that.

2) Tolerance (unit of length) => if lines doesn't match perfectly, end points are glued if nearer than tolerance

3) Sections => they are the sections of struts, they must be planar on YZ plane. Zero must be inside the closed curve. You may provide one section for each line. If not the component will duplicate the last section. 

4) Rotations (radians) => they are used to rotate the sections. By default it is 0. If you provide enough rotations you can turn all the section independently.

5) Clearance (unit of length) => it is a value used to separate struts 

6 to 10 ) bulges factor used to shape the geometry. Use a 0 to 1 slider.

11) Inflate (0 to 2) : It is a factor used to inflate or deflate the node

12) OneNode (bool) : used to calculate one node if true, all nodes if false. If true it is faster to make modifications and you can adapt modification to your node

13) Number (int) : The node number to calculate if OneNode is true

14) Blend (0 or 1) : if 0 it is Rhino Blend is used if not my blend is used.

15) Deviation (0 to 1) : "Relative deviation of points from a plane
16) Ratio  (0 to 1)  For two triangles to be considered the ratio of the resulting quad's diagonals (length of the shortest diagonal)/(length of longest diagonal) has to be >= minimumDiagonalLengthRatio, 0.875 by default
17) Angle tolerance (radians): Used to compare adjacent triangles face normals. For two triangles to be considered, the angle between their face normals has to be <= angleToleranceRadians by default 0.00314

15,16,17 parameter are used to transform triangular mesh to quadrangle and Ngon mesh.

Outputs

1) Nodes : BREP surfaces of the nodes, not closed

2) Points : Coordinate of the connection between node and struts

3) Direction : Direction at the connection 

4) Signs : Used to orient direction (see example)

5) Rotation : Used to orient sections

6 to 9) are the topology of lines, equivalent to SandBox

10) Struts : open surface of the struts

How it works

Soon some explanation of ngon mesh, when I finish the implementation.

TODO List

Documentation, cleaning C# 

Full Ngon Mesh implementation (partial at the moment)

Component for blending curves. At the moment this component blends curves but it needs connecting lines. So I will try do one in which you just need to feed with closed curves and the component will connect them. 

...

Thanks 

Jacek Jaskólski for the idea "I'd love to see a generic solution for a smooth junction/blend between arbitrary shapes meeting at arbitrary angles... :"

peter fotiadis and Charles Fried for their numerous discussions on the subject. 

Aidan K for making Intrallattice and putting it on Github, when clean I also hope to put the component on Github.

Mateusz Zwierzycki for Incremental convex hull, I think I will do my own convex hull as I need face with more than 4 vertices but also faces with 2 vertices !

And many others David Rutten for its superb tool, Mc Neel ...