How to actually use custom UI in game (scaling problems)

Let me prefece this by saying I know about 9-slice and all that. However, what happens if an image can’t use that, as it isn’t an evenly shaped image. If I have this frame for example, how can I size it correctly. Using purely offset would result it unplayable games on mobile/tablet.

I’ve read all the articles on the forums about UI design/scaling, and none relaly seem to go into detail on more complex UI design scaling, and all generally stick to the basic ‘rounded frame’ images

If it’s getting squished one way, you could always build it on an aspect ratio in whatever editor you made it with, then change the SizeConstraint and set it to RelativeXX so that it scales on the X instead of the XY so you can try and make it not squish itself.