So you have a couple of options available to you for the tunic. The easiest in terms of sewing would be to find some sort of coat that looks similar and alter it to fit canon. This will involve lots of shopping in thrift stores and the like, but if you don't want to sew everything yourself, it's a good option. Your next choice is to make the tunic yourself and find a pattern that most closely matches canon. Again, there will be a lot of searching through catalogues, but a lot of times it's easier to make alterations to a pattern than try to alter an already-made coat (for example you'll have extra fabric ready to add things, and you'll be able to get just the right colors instead of trying to dye it). This takes some sewing knowledge because garments aren't beginner sewing projects, but from the sound of your post, you're not too worried about the sewing. Your last option is to draft a pattern on your own. I'd only recommend this if you have past experience sewing clothes, because it isn't easy. It also takes a few trial runs to get right, so you'll have to invest in a bit of cheap test-fabric (or reuse the curtains your friend is so kindly giving away
). For an overcoat like the main characters have it'll be a bit easier because it's not supposed to be tightly fitted to the body (and if you have a feminine figure you'll want to hide some curves anyway). These are your options. All of them will take a considerable amount of time, so choose the one that works best for you. Here's the link to the
Uniform Overanalyzing Thread, which is definitely helpful for getting all those little details right!
As for the material, I'd make it out of something that you would normally wear in early November. I don't know exactly what your climate is like, but where I live, November is cold but not yet snowing. So for me, I might go with a medium-weight fabric like flannel (keeping in mind that you'll be wearing plenty of layers as part of the costume). But if your Novembers are warmer or colder, you may want a different material. You should also take into consideration the weight and drape of the fabric, as that will play in to how closely it matches the comic. Go to a fabric store and play around with the fabrics: you'll find one that's appropriately Reynir-y
And finally, just some general advice: go slow and check everything twice. You don't want your project to be ruined by a wonky seam or a hasty decision when it could have been easily avoided. And don't forget to have fun! Cosplaying is all about having fun after all, and running around goofily dressed as a fictional character
