After looking online for appropriate armor and helmet I was unimpressed and decided to make my own homemade Leonidas King of Sparta costume. Using pieces of poster board I cut the shapes I needed and taped/glued everything together to make my "forms". I then used packing tape over each piece to make water resistant, as my next step was to paper mache each piece (except the arm pieces, I just used a 3d paint for detail then spray painted over).
Once all was dry it got a coat of black spray paint, then a slightly lighter coat of "bronze" spray paint. For the helmet crest I bought a black bristled broom at a cheap store for $3, used a razor blade to cut off the groups of bristles then wrapping a strip of posterboard around the group pressing together with hot glue to make stick together, then glue each group into groove for crest. There is a "tail" in the back of the crest that I used a long piece of "braiding/weave" hair for.
Made the brown trunks myself, making a pattern from newspaper, using a swimsuit as a general guide, actually made a couple before I got the fit right. The cape was a little tricky, I played with the drape and it actually has a "U" shaped piece sewn into the back center to make it drape properly. At the top of the "U" there is a vertical strap under the cape to which there are two slightly angled brown straps attached that go over the shoulders, back around under the arms, then I just pinned them together behind my back. On this strap under the cape I sewed a little pouch to keep money and ID in as I did wear this costume out to clubs (my friend had to get it for me each time, so you could even make it on the back of the trunks, it's under the cape pretty much too).
The broach I made with cardboard and craft foam curved to make more "3d". Covered with aluminum foil and spray painted. I hot glued a strap in the back so I could pull the cape corner through, pin my cape in front, then slide the broach in place. My spear was the leftover broom handle spray painted. then I cut a notch in the end, took poster board - cut 4 triangular pieces, folded each one in the center, then glued each side to the next piece creating a "4-pronged" spear point, did a similar thing on the other end, but I rounded those pieces, then sprayed the tips bronze.
I made a sword out of several layers of posterboard and cardboard all hot glued together and spray painted. I made a fairly simple sheath for it out of some fake leather that is just pinned around my waist (or hips actually). For my shield, I started out with a cardboard circle the size that I wanted, but cut out the middle so all I had was the outside rim. Using apx 1 inch wide strips of posterboard (again), glue one end to the rim, then going directly thru the middle glue across on the other side of the rim, but using some slack so that the middle of the strip "bows up" about 3 inches from a flat surface.
Working around like a clock, I did this with more pieces until I had kind of a "bowl" when you turned it upside down. I added crosswise pieces and hot glued to give more strength, then covered with packing tape before paper mache-ing inside and out. The "V" on the shield was added with corrugated cardboard before the paper mache. I added straps inside (hot-glued) and spray painted.
Leg armor was done in a similar paper mache fashion using 2 lither coke bottles as size forms. The squarish design on front was made with corrugated cardboard again. I used a good hole puncher along the back edge and strung black yarn in shoelace fashion to secure. Same with arm pieces. I actually had the necklace and brown sandals already. Spirit gum and fake hair to add a beard, a little smoky eye makeup, and there you have it.
Oh, and I worked out like crazy two months before wearing this for Halloween, but still needed to shadow the abs in with a little brown eyeshadow. At least my stomach was flat that most people really had to look to know the difference.