If a feller wanted to make a tartan patch to mount on a TOS...and then affix a clan badge or paratrooper wings, etc....what would it look like and how would it be made?

Anyone have a simple pattern or set of instructions or dimensions? I saw one on a WWII re-enactor's TOS but didn't take the time to examine it closely. I think it was square.

Mods, I was conflicted about where to put this...if it needs to move to DIY, so be it...thanks.