I think I've got it.
But some steps needed to be taken differently from how you described it. Could be because I am too silly.
But I found out that,
-after duplicating the original image (so you save that in its original version!),
- you have to FIRST rotate it either horizontally or vertically, whatever are your plans,
- then copy that flipped version (so that copy stays in the memory),
- flip it back to normal,
- then double the canvas size (new part of canvas will be grey),
- and then paste the previously copied (flipped) version of the picture into that grey area (outlining it first, saying "paste" then).
If you then want to make a
four-fold kaleidoscope,
- you have to flip both images,
- copy them - this time using the "copy merged" button (so again the flipped version stays in the memory),
- flip it back,
- double the canvas size
- and paste the double+flipped version in there.
This is what I managed to get out of these steps:
Links gone
You think I got it?
I, for my part, feel positively hooked!