Hey there!
This mod does the same thing as you can see in its name - it gives every single windmill a unique appearance.
I've been bothered by the windmill at Salvius Farm - it doesn't seem immersive for me cause it wasn't made in dwarven style like the rest of the Markarth outskirts. When I fixed this one problem, I decide - why should I stop only on the Salvius Windmill? I can change all of them! So, this is why the mod came to life.

Then I decided that every windmill deserves a unique appearance, and, even more - unique wingsails, decorated with beautiful ornaments, representing the power and wealth of their owners.


How lore-friendly and historically accurate is this mod?
AFAIK due to the representation of the windmills in ESO, there shouldn't be any questions about lore friendliness - as to my opinion, this mod is lore-friendly enough to be included in your modlist - especially if you've already read this far.
And what about historical accuracy? Actually, canvas sails oт the windmills were not common in the world - but not because of the price of the canvas (it was an affordable good for "middle-class" people) - because they don't add much windage to the wing and, therefore, mostly useless if there were actual wooden wing on the windmill. But they existed.
And what about the colors? Historians still discuss, did the people in the Middle Ages paint symbols and patterns on the sails of their boats or it was just a myth. But there is no discussion that some people dyed the sails of their boats - like, Ottomanian military fleet used a red dye for sails, as some consuls of Ancient Rome make carmine-red sails for their flagship - and even Theseus, the ancient greek hero, had the opportunity to choose between black and white sails. More common ship-owners and captains, however, also used dyes for sails - mostly the cheapest yellow and brown colors to make their sails lesser white (to save the eyes of the sailors and make ship lesser visible for pirates or government ships).
So, I don't see any reasons this practice shouldn't exist in the Tamriel - all Nine Holds of Skyrim spend kilometers of the canvas to produce their colorful banners and flags - and some nobles or just rich people may want to show their power and wealth by the decoration of the biggest and the most visible object of their property - the windmill.


There are only 9 vanilla windmills in Skyrim -  and if we exclude Solitude EEC Gates Windmill, only 8 of them are represented in the farms.
Full list by the Holds:

Whiterun - there are 3 windmills, located near the outskirts of Whiterun City.
2 of them are owned by local noble families - Battleborns and Chillfurrows, and the last one belongs to Severio Pelagia, a retired war veteran.
1. Battleborns' Windmill - though this clan is the richest family in the central Skyrim, the sails of their windmills are colored by the golden dye and the pattern shows the fearless nature of the true soldiers of the Empire. Their windmill is covered by fresh plaster, and inside you can see new planks.
2. Chillfurrows' Windmill - the most ancient family of the Whiterun Hold, nowadays going through the harsh times. The pattern of their wingsails represents the unbreakable chain of generations from the 500 Companions of Ysgramor, and the blue color of the background symbolizes the current political sympathies of the clan's patriarch - loyalty to Stormcloaks. Their windmill itself looks very old, plaster and wood are not in good condition.
3. Pelagia's Windmill - as a person, who served in the army, Severio Pelagia wants to show, that, even he is new to this land, he is no worse than his noble competitors - so, he colored the windmill to the colors of Imperial Legion. The pattern shows an inseparable growing plant, that symbolizes rich crops. The windmill itself is the poorest one of three, made with uncolored planks for walls and the roof.

The Rift - there are 2 windmills, one of them belongs to the Snow-Shod family and another one - to the Sarethi sisters. Both windmills use Riften textures.
4. Snow-Shod's Windmill - the part of the big farming complex, located in the woods, this windmill carries the Show-Shods' clan pattern on its sails - the line of snow-shoes, following one direction. By the color of these symbols, you can guess the political views of the owners.
5. Sarethi Windmill - part of the property that belongs to two sisters, talented alchemists. Long ago they were just refugees, who left their homeland - and now they hunt for the rarest plant in the world. Red nirnroot is depicted as their family symbol on the green sails (and green is the color of nature and alchemy).

The Reach - there is only one windmill, located near the hold's capital.
6. Salvius Windmill - the property of commoner Salvius Family. The windmill itself now is made of dwemeric stone, like other buildings in the Markarth area. As the Salvius family is not rich nor noble, the sails are blank. weathered and gray.

Haafingar - this hold has only 2 windmills, and both of them are located in the capital area. One of these mechanisms is the Grand Windmill of the EEC Gates, another one belongs to Katla.
7. Katla's Windmill - the property of Katla's family. These people are not noble nor rich enough to afford the colorful sails, but their windmill silo, as in the vanilla game, carries Solitude textures. with minor fixes to the model itself. Also, in the main version of the mod, the sails are enlarged perfectly to avoid clipping issues both with vanilla and Mathy's meshes - so, I didn't touch the mesh of the wings.

The Pale - cold and inhospitable lands of the Pale have only one area for crops - the southern border with the Whiterun Hold. The only windmill of the Pale is located in the Loreius Farm.
8. Loreius Windmill - it remains completely untouched by me but I strongly recommend you to download an awesome mod from Mathy79 - Skyrim 3D Windmill. With this one mod, mine will work as on the screenshots - every single windmill will be beautiful and unique.

Technical details: there are 2 versions of this mod - the main one and the optional one.
The main one - slightly change the size and the position of all windmill wings except the ones from Loreius farm.
The optional one - doesn't change the size and position of windmill wings, the only changes are the meshes mentioned above.
Both versions are ESP-LE so the mod won't take space in your load order.

This mod uses vanilla or Brumbek's textures for windmills and their wooden parts - the only new textures are the canvas sails. So, the final appearance of the windmills depends on the textures you use in your modlist.

Compatibility:
This mod is compatible with almost everything except the mods that change the same objects in the world - mods, that change windmills.
Incompatible with:
SMIM Windmills Resized
Bigger Windmill Sails for SMIM
Proper Windmills of Skyrim

While there will be no problems if you will use these mods alongside mine, you will not get the changes from both at the same time and the mod, closer to the bottom of the load order, will prevail.


Credits:
This mod uses resources (meshes and textures) from the awesome SMIM mod by Brumbek. I really appreciate the permission he gave me to use them.
This mod works perfectly with the Skyrim 3D Windmill from Mathy79.
This mod will be developed in the future - there will be changes in models and textures.
Gratitudes:
Thanks to the NifSkope developers.
Thanks to Google I used to search for patterns.
Thanks to the Paint.NET developers.
Thanks to xEdit developer ElminsterAU. The first version of this mod was done completely by this tool.
And of course, thanks to Bethesda Game Studios and their greatwisest lead, Godd Toward Todd Howard
Permissions:
You can use the idea of this mod to create your own mod.
You can create new skins for the windmills in this mod.
You can include this mod in collections.