How to "unify" a series of curves?

[Khis]

I have made a pencil in affinity from a series of curves/lines now that I am done I would like to make the pencil entirely one shape. Whenever I select the nodes and use the "Join curves" tool, The curves become one shape except that some lines are created that sort of close the shape or connect them in a weird way. I have added the images for a better understanding of what I mean. How do I stop this from happening? Thanks.

Edited May 5, 2019 by Khis
Adding another picture

[R C-R]

As constructed, you can't really stop that from happening, other than by making the path one continuous curve, which typically requires doubling back over parts of it & is usually tedious to get right. Basically, this because a vector curve can have no more than one start node & one end node, which may be joined into a single start/end node (using the "close curve" action).

Also note that a vector shape can have only one stroke & one fill color property (which could be a gradient), so for example you could not color the eraser, ferrule, lead, etc. different colors.

To avoid this problem, it is best to think in terms of shapes rather than individual lines & curves. Most of this design can be made from rectangles, & by clipping some of the shapes inside others, you don't even have to be careful about lining up all the edges. To see what I mean, consider how the 2 pencils in this pencils.afdesign file are constructed.