Bear with me on this because I want to explain what I'm trying to do first. Shutterstock has an option to try a piece of stock before buying it. You can download a small, watermarked version of an image to see how it will look in your piece.
I want to be able to do the same thing with furnishings on ESO. When you go into the Crown Store from the Housing Editor, you can preview an item to see what it looks like, but not how it will look in your house. Measurements only go so far. I've wasted I don't know how many Crowns buying something that doesn't work in my house. I've sent ESO feedback, but I don't really expect a response on that any time soon.
I don't want to necessarily download the piece altogether, but more I'm looking for a way to add to the Preview menu to try it out in the home, and then it would disappear if you don't buy it.
Does anyone know of an addon that will do this, or would someone like to collaborate on a new one? I'm not a coder, but I can still offer input.
This won't be possile as the addons got no way to get crown items as preview, the crown store is totally capped from addons afaik.
So I doubt there is any way creating any preview you could use in your house, or it would exist already.
I've always wondered the same. It's really hard to tell how an item will look in the house just from the preview and even harder to know all the existing items, what they look like or how to get them. It would be really cool if ZOS added some kind of "creative mode" where we can just browse and use all furnishings that can be earned in the game, but it's only visible to ourselves and half transparent until we get the necessary furnishings to build it for real. Once a required item is in the inventory, it could then offer to place it in the house where we put it in this creative mode and piece by piece realize whatever we came up with.
Unfortunately as Baetram says, it's not something that can be done with addons (or rather it would require to replicate every single furnishing in a way so that an addon can generate a 3d preview, which would be an impossibly huge undertaking).