I've never made a Mandalorian costume before, but I know there's sites out there that can help with that. Try googling it.

From what I do know though, you'll have to buy the helmet from somewhere, either starwarsshop.com or ebay or something. I'm not sure which brand of helmet's best, though. For the flight suit just some grey-blue cloth sewn into jumpsuit style. Or if you really want you can try to get one of those mechanics coveralls, they're kinda the right color. Armor building I don't know anything about. The Wookiee braids can be done by buying some of those fake hair extensions maybe.

But don't trust me on any of that, the sites and other members here are more knowledgable on this than I am.

Thanks so much! I looked on ebay, they had peices of the armor and some completed costumes but I'm tiny any theres no way it would have ever fit. Ebay had helments too but I'll try starwarsshop.com.