a) I have created two rectangles and now want to draw a line between each corner to make a 3D cube shape. (Join selected end nodes doesn't work as there are no end-nodes.)

How to do this for any two 'closed' paths of any shape?

b) Draw two lines with multiple nodes. How to draw a line between an inner-node on line X and another on line Y ?

c) How to move a node on path L to a node on path M and have them...
.. c1: snap so that the path L node snaps to the same position as the path M node?
.. c2: snap and weld together so they become one path.

Thanks for any help.

ps - I read the advanced help stuff but I guess I missed how to do the above.

A node can only be connected to one node or two. Three is not an option using Inkscape and SVG. you have to create an unconnected path or sub path and use snapping to situate the end nodes precisely on top of the target node or path.

Other possible ways of drawing a cube is to use the extrude extension.

Or the 3D box tool (Shift+F4).


Or just use the render 3D polyhedron extension.

Isn`t that bad? I mean, three is for a charm, right?!

While I presume Lazur`s suggestion would work perfectly right.

1 - is there a create 'sub-path' tool?
I have the two rectangles and have hit Ctl K to combine them into related sub-paths.
Next I select them both and press F2 to edit paths
Next I thought there may be an option to create another related subpath but I guess I'm missing it.

So I created the four lines, selected them along with the two rectangles, and then hit Ctl K to combine them into related sub-paths.
Then I took the end of each line and dragged it over to one of the rectangles corners so that it snapped into the same place.

Is this the only way to do it or is there a 'create sub-path' tool that will allow you to create a subpath related to the currently selected paths?

2 - Once the nodes are co-loated (line end to corner) it seems the only way to move that corner and line end-point is to drag a box around both nodes... as they are not "welded" together... right?

3 - I clicked four buttons to get snap to work... (snap a line end to a rectangle corner) is this what yo have to do or what?
click...
.. Enable Snapping
.. Snap Nodes or Handles
.. Snap to Cusp Nodes
.. Snap to Smooth Nodes

Thanks again for the help folks.

1. There is no sub-path tool.
   You either use the pen tool (Shift+F6) to draw the segments you will combine with the rectangles, or use the node tool (F2) to edit them out from the existing ones.
   To do that for example, double click to add nodes to a segment. For a new sub-path, add two new nodes to a rectangle's path segment somewhere,
   unconnect segments between the original nodes and the new ones, then connect the original nodes back together.
   
   On a side note, combining paths is not always necessary nor handled well by the renderer.
   Usually it causes issues only with high node count paths, with 5000+ nodes.
   Another way to organise objects together is grouping.
   First, convert the two rectangles to paths (Ctrl+Shift+C) -or in this case you already combined them, break it apart (Ctrl+Shift+K)-
   and group them together (Ctrl+G).
   To enter the group you can double click an element of it or press Ctrl+Enter when selected, then you can select objects in it.
   Like, this case you can enter the group of the two rectangular paths, select one of the rectangles,
   duplicate it (Ctrl+D), then with the node tool split all the four nodes of it, and break apart, to have four paths with two nodes, exactly what you wanted to draw.
   
2. As an object, they are welded together, as nodes, they are not.
   If you want to edit them together, you need to rectangle select such a "double-node".
   
3. For this drawing, snapping to smooth nodes is not necessary.

Good luck!

Lazur (and others) thanks for the great help.

I'm trying to learn how create solid 3D objects...
.. example 1: https://www.learningpod.com/question/pr ... 8b1e30f1b1
.. example 2: http://www.goodingalum.com/p10/c179/Alu ... le-Unequal
etc.

it looks like subpaths won't work as making the visible sides of the 3D object not-transparent doesn't seem to work...

Are there any tutorials on creading 3D parts or objects?

Thanks again.

So you want to draw in cavalier axonometry.
The extrude extension can cover that mostly.
You have to ungroup the resulting object, delete unnecessary sides, set an opaque fill and change z-ordering if necessary.

There is a recent topic on how to "flatten" paths above eachother with white fills and black strokes into one path, but that's not necessary for such simple drawings.