Unbelievably easy to do.
Just a VERY short, hopefully, simple to follow tutorial.
I've included some alternatives. I'm not married to MY
model, MY tutorial. If something else floats your boat,
have at it. I just haven't seen this on the web. And,
as you'll see, I've looked.
From my first tutorial, there's Blender Basics if you
need them - recommended, if you do.
Let's get to it.
Step 1: Basic Overview
Instructions - Also INCLUDED in the blender file:
26 point Moravian Star (Augmented Rhombicuboctahedron)
There's this on Instructables:
Moravian Star by rwinscot
A Modular Origami Star by MakeMom2:
A video on making one in Blender. It's a speed modeling tutorial.
Hard to follow - more complicated. But, if you're interested:
And a completed model on Thingiverse:
You'll need the (built-in) Math Function (Regular Solid) for this.
It may be there by default. If it's not there, you'll need to add it from
User Preferences / Addons.
Here's a quick tutorial on it:
Select (Ctrl-A) / Copy (Ctrl-C) / Open Text editor of your choice,
Paste (Ctrl-V) these instructions and print for easier reference)
01) Delete Cube (Del)
02) Add a Rhombicuboctahedron - Shift-A / Mesh / Math Function / Regular Solid / Custom / Rhombicuboctahedron
03) Tab - Edit Mode
04) Poke Faces - Alt-P
05) Unselect All - A
06) Using Vertex Select, Right Mouse Click on the center vertex in any square
07) Select Similar - Shift-G / Amount of Adjacent Faces
08) Scale - S (Drag Mouse to the Right) - Out to your liking
09) Repeat steps 6 -8 on the remaining triangles
10) Tab to Object Mode
11) Export to STL (Print using method of your preference)
12) That's it. Enjoy.
Step 2: A QUICK Overview of the Process
It takes slightly longer to create than it does to watch this video.
Step 3: STL File
Passed printability tests at Shapeways.
At a little less than 2 inches (xy - width / height), it costs
about $ 9 to print.
Less, of course, if you have your own (or access to a local
3D printer) - Tech Shop or 3D Hub: (US)
Good for a tree ornament.
Not so sure you'd want it on a tree top.
Possibly Pepakura can provide a less expensive,
more sizeable alternative.
With 26 points, it's sure to be a bit of a challenge.
(Note the Bonus below only has 12 points by comparison,
and there's already "nets" out there for it and others
Nets: Unfolded Polyhedra diagrams which can be printed
and folded to form various Polyhedrons:
Step 4: Bonus File - SSD
That's Small Stellated Dodecahedron.
Same process. Easier because all sides of the
dodecahedron are pentagons. Easier to select
and scale outward.
If you tackle it in Blender, just make sure, in edit
mode, that you Delete / Limited Dissolve.
Those extra edges can be a design killer.
As suggested above:
Small Stellated Dodecahedron nets:
Questions? Suggestions? Problems?
Let me know in the comments. Enjoy.
Almost forgot. I did print out the SSD (cutout) some time
ago. Cost about $ 10 on Sculpteo.
Difference is I applied Inset to the Faces. Deleted the
Inset and then played around with the thickness for
Step 5: Addendum - If This Kind of Thing Interests You...
You might also be interested in:
Polyhedronisme - Online Polyhedron Generation / Export
JS Modeler Solids Examples: Generation / Export
and, last, not least:
Kit Wallace's Polyhedra in Openscad (A LOT of Polyhedra): Generate / Export
REQUIRES Openscad Free 3D Design tool (Exports STL format):
And I promise, I DO have a life.