Just fresh out of the oven, this one.
Simple but fun.

You can get the plug-in here --> Sample Color Border Plug-in

version 2 is out. Superior to version 1.

Is this a frame /plugin made similar to the kaleidescope way?

It's similar because it's also a frame/border.
But it's different because it doesn't do kaleidescope but it samples numbers of colors (well by turning your image to indexed mode of specified number of colors)
Then it uses those colors to create the frame while keeping the color proportions the same (relatively) so for example if you have a lot of white in image relatively compared to other colors in image, then the frame will have a lot of white (relatively compared to other colors in the frame)

Hi Tin Tran.

This plugin has a very big potential for further development - sorry, but I had to try (as part of learn Python )...
and I added a few options.
Thank You for new plugin.

right on! That's way above my head (I am happy you're able to use it to add on top of what's already there).

Like to know how you got the round 'feathered' one

Lovely image sallyanne....

Agree! nice image, Sallyanne. To get the "feathered" look it is in the script dialog when you choose elipse, and then distort, set the other parameters.

Rel 1.2

The original plugin works on the selected layer - but transfers all layers to the new image - I changed it to only move the layer to which you want to add the frame.
I also added a new option - bevel (but it works differently than presented by Blighty on GimpLearn in the post:
https://www.gimplearn.net/viewtopic.php?p=24004#p24004
because it's based on another plugin, which is in the GIMP 2.10 standard - "add-bevel.scm" and not "GT Bevel.scm").

Doesnot work for me (gimp2.10.8 on Linux). Registering failed for some reason. I checked my plugins and script dirs but they are correct.

MareroQ, round distort effect is awesome. Can you fix this problem?
The distortion expands over the canvas, and after resizing you can see that it's cut off.

@Moroquendo
For plugin enable executable permission for admin/user ?

@Nidhogg
Thanks for testing - I think in ver. 1.3 it will work better.

................................................................

Ver. 1.3

Change Log:
- Fixed a bug for "Ellipse Distort " (the spread was no limited) reported by Nidhogg.
- Add elements of the plugin "Pespective Border.py" created by Tin Tran
https://www.gimplearn.net/viewtopic.php?f=3&t=2142&sid=bc4ab6263118fc983f39bd7e627d8a3f

Thank you for update MareroQ

Stupid stupid I should have known that. Thanks it's working now.

Rel 1.4

- add type: "Free select" (any selected shape),
- add option "Distort" for all type except "Pespective Border"

PS. I will probably finish this version because I should start with this "Free select" (since any shape can be framed it seems unnecessary select: square and ellipse) ... but I like to learn Python.

Rel 1.5

- Fixed a bug for "Pespective Border" in ver. 1.4
- add option "Invert sample"

It's hard to keep up with Tin Tran.

Ver. 1.6

- fixed a bug for "Ellipse",
- add option: Merges all visible paths to the selection (replace) - a little easier when using e.g "Unicode_to_shape",
- add efect type: "Drop Shadow".