varxtis,
Sorry, I could see the screenshots clearly the following day; maybe Firefox was overloaded so the page failed to load fully when I first looked at it.
I also apologize for the rather late answer. There were a few urgent other tasks, and this snowflake challenge grew on me, to the extent that I thought of splitting the answer into two posts.
Here it is:
Looking at the images, I could see an obvious potential for a new feature or two, so I have made a feature request about an enhanced Miter Join.
It is here for possible votes and comments:
Basic properties/possible feature request(s)
This is based upon the first three rows in the image below. I will spare you the exact details and calculations, which are known to our Design Team friends at Adobe, of course.
The first row of stroked triangles shows some of the basic properties of Miter Joins and Bevel Joins: To the left is a black triangle with a sufficiently high Miter Limit. In the middle the first triangle is overlaid with a red Bevel Join triangle (or a Miter Join triangle where the Miter Limit is too low, which makes it default to the shape of a Bevel Join). To the right the two triangles are overlaid with partially transparent white open paths with Butt Caps; their ends cross at the corners of the spine of the triangles, and their outer edges end at the corners of the Bevel shapes. As it appears, the Bevel sides lie outside the corners of the spine, rather than passing though them.
The second row of stroked paths with a rather sharp angle at the top (corresponding to a Miter Limit of 8 ) shows a symmetric way an enhanced Miter Join could work (1 is the lowest selectable Miter Limit and effectively comprises a Bevel Join): Under each path the quotient shows the chosen/required Miter Limit, and the effect of the enhanced Miter Join is a shortening of the Miter shape to a blunter angle which corresponds to the chosen Miter Limit, like the tip of an obelisk or a metal chisel; the faint grey line behind the shapes shows the Bevel Join height, and it appears that the transition is indistinct at high values and obvious at low values.
See Also
Betreff: multiple path closureTutorial: How to create a learning path quickly and easily in Chamilo
The third row of stroked paths with a rather sharp angle at the top (corresponding to a Miter Limit of 8 ) shows an asymmetric way an enhanced Miter Join could work. This corresponds to the second row, but is one sided so only the left side has the blunter angle which corresponds to the chosen Miter Limit, resulting in an asymmetric shape somewhat like a wood chisel with a sharper point for the same Miter Limit; in the corresponding mirrored shape only the right side has the blunter angle.
A Stroke palette Enhanced Symmetric Miter Join feature (request) could consist of suggesting two options for the Miter Limit, namely Obelisk and Default, where Obelisk gives the shortening corresponding to the chosen Miter Limit and Default gives the Bevel Join shape.
Or, more comprehensively including the asymmetric version, a Stroke palette Enhanced Miter Join feature (request) could consist of suggesting four options for the Miter Limit. These could be Obelisk (as in the first row), Chisel Left (as in the second row),Chisel Right (as in the second row, only mirrored), and Default, where Obelisk and Chisel give the different kinds of shortening corresponding to the chosen Miter Limit and Default gives the Bevel Join shape; it could be one Chisel option with the additional options Left and Right. As an alternative, the options could be Chisel Center (as in the first row), Chisel Left (as in the second row),Chisel Right (as in the second row, only mirrored), and Default; it could be one Chisel option with the additional options Center and Left and Right.
More flexiblly, an alternative/additional Stroke property Enhanced Miter Join Tool feature (request) somewhat corresponding to the variable Width Tool and to Live Corners and applicable to one/more/all joins, could consist of suggesting the Obelisk/Chisel Center and Chisel Left and Chisel Right and Default as Miter Join Styles options, corresponding to Corner Styles, in connexion with something similar to the two forms of adjusting Live Corners, namely by inserting values of Miter Limit similar to Corner Profile, and by dragging similar to dragging the Live Corner Widget.
Even with such a feature request (set), you will have to continue in a more laborious was until the feature request is implemented or till the end of time, whichever occurs first.
To be continued under the image.
A few solutions to the present case
What you need is shown in some of the snowflakes in your first image where the outermost parts of the outer shape are less sharp/more blunt than the corresponding inner shapes, in some cases forming two angles, more blunt at the tips, just like the suggested Miter Join Obelisk option. In connexion with those snowflakes, you have Compound Paths, and the inner and outer paths are only partially related, if at all.
For your own very customized snowflakes, you may proceed in a few different ways, depending on how regular or irregular/freeform you wish to make them.
The image above shows three ways, A1 - A3 and B0 - B6 and C1 - C3, on the common blue background. All three ways start out with a tormented (default) 5 point star consisting of a red filled path and a set of white/pale blue stroked paths (with sufficient/insufficient Miter Limit) behind the filled path, the upper right and left points to be shortened. All three ways require outlining of the stroke(s).
The Line Segment Tool and Smart Guides are your friends. Remember to lock the background path.
The instructions below apply to the image above, so you need to adapt to your snowflake case(s).
If you wish to go freeform with symmetric Obelisk/Chisel Center shapes, you may:
A1) Start with the red filled path, then Ctrl/Cmd+C+B to create a copy behind the original and switch from red fill to white stroke and set the Stroke Weight and select Bevel Join, then Ctrl/Cmd+C+B to create a second stroked path and change to a pale blue colour and Miter Join with a sufficiently high value, then outline both stroked paths, then with the Line Segment Tool ClickDrag between the points of the red path and the pale blue path to create a black temporary line for each point to be shortened;
A2) With the Add Anchor Point Tool click the Bevel part of the white path beside the black line, then switch to the Direct Selection Tool and ClickDrag the added Anchor Point outwards along the temporary line until you have the desired shape (you may go back and forth and readjust both points until you are satisfied);
A3) Hide (if you wish to be able to redo later, when the entire shape is as desired you can always delete later) the temporary lines and the pale blue path, and select the red triangle and Ctrl/Cmd+C+F+X+F to bring it to the front.
This gives you the opportunity to customize the Obelisk tip shape at each point in different ways; I applied Object>Path>Add Anchor Points to both temporary lines and simply ClickDragged to the added midpoint, thereby shortening the shape to one half the original length for both points.
If you wish to use a certain angle/sharpness at the tips, directly corresponding to thesymmetric Obelisk/Chisel Center shapes option feature (request), you may:
B0) Create a (less) pale blue filled triangle with the desired sharpness of the tip angle (pointing upwards), then Object>Path>Add Anchor Points, then delete the added Anchor Points in the slanting sides (with the Delete Anchor Point Tool) so only the midpoint at the bottom remains;
B1) Do as in A1), only reverse the colours of the stroked paths and extend each temporary line inwards (in the Transform palette you may click the relevant upper corner Reference Point and multiply the W by 2 or something and press Ctrl/Cmd+Enter);
B2) With the Selection Tool Alt/OptionClickDrag (a copy of ) the triangle B0) by the lower midpoint to snap to the temporary line close enough (see B3)) to the inner end, then switch to the Rotate Tool and Click the midpoint (to set it as the centre of rotation) and ClickDrag the top point round to snap to the line further outwards;
B3) Switch back to the Selection Tool and ClickDrag outards along the temporary line until the sides of the triangle reach the corners of the Bevel shape thereby only just covering it;
B4) Do as in A3);
B5) - B6) Select both the triangles and the Miter Join shape and combine/trim/recolour them, depending on version you may use Pathfinder>Divide and delete the unwanted bits and Pathfinder>Unite, or you may use the Shapebuilder Tool, see below.
This gives you the same Obelisk tip shape at both/all points.
If you wish to go freeform with asymmetrical Chisel Left/Right shapes, you may:
C1) Start with the red filled path, then Ctrl/Cmd+C+B to create a copy behind the original and switch from red fill to white stroke and set the Stroke Weight and select Bevel Join, then Ctrl/Cmd+C+B to create a second stroked path and change to a pale blue colour and Miter Join with a sufficiently high value, then outline both stroked paths;
C2) With the Direct Selection Tool and ClickDrag the desired Bevel shape Anchor Point outwards along the Miter shape until you have the desired shape (you may go back and forth and readjust both points until you are satisfied);
C3) Hide (if you wish to be able to redo later, when the entire shape is as desired you can always delete later) the pale blue path, and select the red triangle and Ctrl/Cmd+C+F+X+F to bring it to the front; I applied both Chisel Left and Chisel Right, the opposite asymmetries producing a degree of overall symmetry.
This gives you the opportunity to customize the asymmetric Chisel tip shape at each point in different ways. As it appears, this is simpler than for the symmetric tip shape shown in A1) - A3).
A similar way can be used to create asymmetric shapes with a certain tip angle, simpler than B0) - B6).
https://helpx.adobe.com/illustrator/using/creating-shapes-shape-builder-tool.html
It may be noted that the Shape Builder (along with its family member Live Paint) is less exact than the Pathfinder, see this post by Ton,
https://community.adobe.com/t5/illustrator/measurement-precision-fail/m-p/10562216#M141790
