This really belongs in the "general cosplay [crafting]" section but I'll add to the answers.
I agree with the cardboard & paint technique, but I suggest chip board over corrugated (the solid kind like on the back of a pad of drawing paper vs. the type shipping boxes are made from). Tin snips work better than craft scissors for small detail cuts on this kind of material. Big cuts need to be made with a straight edge and good sharp utility knife. You can draw out the shapes in a teselation then cut. Kinda sorta like this, but long tall shapes. http://www.testmobileview.com/best-3...ing-page-free/
sewing will work, but brads should hold just as well and be way faster. plus they will look more like the rivets used in the original costume. the only drawback to this is the underneath shirt you use needs to not be a stretchy tee and you'll want an undershirt to prevent the brads from irritating your skin. Don't know how available this is in the UK but it's a godsend when it comes to punching holes in thick materials: http://www.joann.com/crop-a-dile-ii-big-bite-punch/9732801.html?mkwid=nRgpLb8N|dc&utm_source=google&u tm_medium=cpc&utm_term=&utm_campaign=Shopping+-+Scrapbooking&CS_003=12309626&CS_010=[ProductId]&gclid=Cj0KEQjw5Z63BRCLqqLtpc6dk7gBEiQA0OuhsFlHzFE 5vJDPFw_nsY4wBM1fU29I_kS7fcIoV7lpX6oaAl7W8P8HAQ
brads, available in lots of colors and sizes; http://www.shoplet.com/Gem-Office-Pr...ftwaAoVS8P8HAQ
OH and another thing: hot glue is not for flexible surfaces. if you hot glue your shapes onto a garment, they WILL peel off with movement eventually.