BacklightSora- The belt is acctually one of the most simple things on the entire outfit. The best way to make it is to go find a good leather belt. You can get something good for 10-15 dollars if you know how to find the sales. Kholes is usually a good place to look and they almost always have their belts on sale. THe next thing you will need is good acrylic paint. I prefer the Basic brand found at most craft or art stores. You can pretty much find the exact shade you want as they come in a variety. The smaller tube will be more than enough for this. The reason I like this kind of paint is because it is flexible and bonds really well to leather. I've acctually used this to paint shoes I needed a certain color they didn't sell. I would suggest you get a blue color that matches, a white, and a silver. (Most places like Michales have 40% off coupons every week or sometimes Sunday specials for a percentage of your entire purchase. They also go on sale from time to time)
Once you have that. You simply paint the belt blue leaving space on the end for the silver end piece. You may have to add a few coats of paint but no more than three. It just depends on the belt. Once you are finished with that you paint the left over spot white before painting it in the silver. The reason for this is the silver can be a bit thin and doesn't cover completly without a few coats. This should cut back on the amount you need to use. After it dries you have your finished belt. I'll post my Rikku(FFX) belt I made in the same way to show you what it will look like.
Option2 for the end part- If you want a more accurate end part or aren't happy with how the paint looks you can make it out of craft foam. There are several different thicknesses you can get to match the belt and most sheets of it cost less than 3 dollars. All you have to do is cut the shape out and paint it. I still recomend getting a white craft foam and painting it silver. Once the end part is done you can glue it to the belt using E-6000 glue. Again you can find this in most craft stores. I've used almost every kind of glue out there and I highly recoment this kind. It bonds anything to anything. This method is a millon times better than sculpy clay. For one it is lightweight and won't turn your belt into a weapon. Not only that, you will never have to stress over it breaking. I have used sculpy to make a belt buckle for a Star Wars costume and it lives in buble wrap when I'm not wearing it and I'm constantly stressing over it breaking or comming off when I do wear it. Costumes should not stress you out!!
I hope this helps and believe me, I understand the stress of finding belts and things like that which match the costume you are making. I think it took me 4 months to find a double holed belt for Rikku(FFX).