Q:

How do I make a tileable texture with an outside textured border in Maya?

TLDR version:
How do I have a tileable texture with an outside border in Maya?
Specifications: I am running Windows 10 Home, Autodesk Maya 2018, and Unity 5.6.1f1. This is a Maya question, but I want to put the finished model into Unity and have it also work.
Long version with my ideas (probably need to read this to understand, honestly):
I have a ceiling I'm trying to photorealistically texture from real life. I'm making a 3D model of a room in Maya. It's a stucco ceiling. I found a tileable stucco texture that's perfect. Problem is, my ceiling has a 4-inch rim around it that is not stucco - like the wet drippy paint was smoothed down only around the edge of the ceiling, for aesthetic purposes.
I want to take my ceiling plane in Maya and slap the tileable stucco texture on it, but then I'll have no smooth rim around.
I could photoshop-create a "whole ceiling" texture by copying the tileable image until I get a ceiling the right size, and then photoshop on a smooth white border around the image. But then I'd have a HUGE high-res image to read in, and if I ever want to change the size of the ceiling even a little bit, I'd have to remake the texture, instead of letting my gorgeous tileable texture take care of it for me.
I want the ceiling to just be one plane, but is there no other option than to make it two pieces of geometry: one plane for the stucco inside, and another mesh around it for the plain white border?
Can I possibly put multiple materials on the ceiling plane? Maybe adjust the vertices so there's faces that cover the border only, and choose for only those faces to be a plain white ceiling texture, and have the rest be my tileable stucco pattern? Is that a thing that can be done? And is it a good / the best idea?
Is there maybe some way to put the solid white border and the tileable pattern into one texture, and tell it to only tile one section of it, and use the other section of the image for the borders?
Okay, that's everything. Any help would be appreciated, thanks in advance!

A:

This is really more of art production question than a general purpose programming question, so SO may not be the best place; you might want to try cgSociety or tech-artists.org.
That said, you can probably get what you want with a relatively straightforward shader. You can tile a conventional stucco texture across the ceiling and use a bit of simple math to use a simple function either turn down the stucco normals or blend to a different normal-color texture pair. If you have written shaders before it's pretty easy. If not, however, there's a bit of a learning curve associated with getting a shader going for the first time that's probably out of scope in this context.
Your fallback plan -- basically creating some inset geometry and applying a different shader -- is totally doable. It's less flexible than a shader-based solution but it's easy to do *you can use the 'extrude' tool in Maya, setting the depth to zero and using the 'offset' value on it to create the inset rim.  It will even handle non-square ceiling shapes.  The separate geometry/shader option will leave a hard edge between the stucco and the rim, which may or may not be perceptible in the shot you're actually doing.  

