That scythe looks like hell to make...but on with it!
Okay. First, the handle. Find sturdy wood at lumber supply stores. Or you can buy aluminum rods at 168 for around 45 php each, and they're about...6 feet long and an inch thick. mmyeah. Problem with the rods is that they're covered in a plastic...wrapper that's hard to remove, and it's going to be difficult to paint if you're not using spray-paint.
The blade itself, you can make out of styropor, shape it, and just papier-mache it all over. (Allow two weeks, a month, tops for this method) Or you can go to a carpenter and ask him to cut it out for you from plywood that's maybe 1/4 of an inch thick. Then sand down the bladed edge; maybe you could ask the carpenter to do that for you. Just show him a reference pic... (Just not too sharp or the security guards won't allow you to go anywhere) It'll save you a lot of time and effort. The paint job...yeah. Up to you.
The chain thing. If you want to sacrifice accuracy for cheapness, there's a fine metal chain going for 15 php per yard at Michelle's ribbon center in Divi. If you want the large links...I dunno. I believe those things are heavy.
The ball of the chain? Styro ball...XD
If you're using wood for the blade it's advisable that you also use a wooden stick.
And that thing is going to be heavy, I tell you.