It appears that dmccooey.com has been fully updated to https, but the addin cannot read https links it seems.

However, there is a way to add polyhedra from the site directly and permanently to the database of the addin. Though, this is a bit of work:

First, find the addin's folder on your computer:

in the AddIns menu, click Polyhedron Generator and on the right click the link to the AddIn folder.

Second, download the polyhedron files

1. Go to dmccooey.com, open the polyhedron you wish
2. In the broweser's adress bar, replace the "html" at the end of the URL with "txt" and press enter. A plain text with cryptic numbers and formulas should open.
3. Download that txt file; I recommend using the "Save as" dialogue of your browser or just press Ctrl+S
4. In the folder or your addin, put the txt files into the subfolders \Contents\shapes\ without making any changes to the files

Third, add the polyhedra to the menu

1. In the addin's main folder, open PolyhedronGenerator.py with a plain texteditor of your choice. Do not use Word or so.
2. Find the first bigger text block starting with "all_polyhedra" in line 9 and go to the end of that block, ending with } and before "def run(context):"
3. In line 48, after "'GreatIcosahedron']" and before } add a , and press enter to create a new line.
   • After each ] except the last in this list, you need a comma, otherwise it won't work
4. In the new line 49 you created add, similar to the other lines:
   'Categoryname':['FilenameOfYourFirstPolyhedron',
   'FilenameOfYourSecondPolyhedron']
   • Follow the syntax in detail; if it won't work, there is proabbly a comma, an appostroph or a bracket missing here
   • Use plain filenames without ".txt"
5. For example, I added two Trapezohedrons and it looks like this:
   'Dipyramids and Trapezohedra':['PentagonalTrapezohedron',
   'HexagonalTrapezohedron']
   • The line break after each line is not obligatory but recommended
6. Next scrool down to the block starting with "# Event handler for the commandCreated event."
7. After line 106 "dropdownItems1.add('Kepler-Poinsot Solids', False, '')" add a new line
8. Insert as follows:
   dropdownItems1.add('Categoryname', False, '')
   • Do not add a comma after this line
9. In my example the line looks like this:
   dropdownItems1.add('Dipyramids and Trapezohedra', False, '')
10. Save the file

Finish and try out

Go to Fusion and in the Addin menu stop and restart the addin or just restart Fusion.

If the Polyhedron Generator does not appear where it did before, there is most likely something missing, in my case the comma after the first "]".

If everything turned out right, you should now be able to find your added category(s) and Polyhedrons in the drop-down menu of the Addin 

Seems like it stopped working with the new updates 

Tool seems great! FYI, when trying to import shapes from the website, it says "problem with connecting to data"

I needed a dodecahedron for a project and this got me started. This simple add in really made my life better. Thank you!

I want to make polyhedron

I was able to run this on OS X by installing the MSI on a Windows machine and copying the files to the appropriate folder on OS X. In order to use it without "Custom Weblink" I had to modify line 231 to have a '/' instead of '\\'. Thanks to the author for publishing this add-in.

After wasting countless hours looking for ways of getting big dual geodesics into Fusion - this shows up. Perfect.

Great add-in! Contains a lot of shapes AND ability to download thousands more from their web site. VERY WELL DONE! Thanks!