First kilt fabric choices?

[OC Richard]

What's the provenance of those "shoulder pads" and breast pocket affixed to the sweater of the guy on the left?

That jumper appears to be based on the jumpers used in the British army.

Here's a soldier wearing one.

They have reinforced shoulders and elbows as you can see. There are slots at the shoulder seams for your epaulette to go through. Officers' ranks are displayed on their epaulettes, and sometimes Sergeants' ranks too, though here you see the Pipe Major's stripes etc sewn onto the jumper.

BTW in the UK they're called "jumpers". I think "sweater" is confined to North America.

About the pocket, I don't think I've seen a military jumper with that.