There are a few things to consider when selecting raw wood for your bow:  Find a piece of dry and dead (but not gray or cracking) hardwood (such as oak, lemon tree, hickory, yew, black locust, teak, ash, juniper, or madroño) about 1.8 meters (about 6 feet) [or as tall as you may be] in length.  The wood should be free of knots, twists or limbs, and it would be helpful if the branch is thick at its center. This piece of wood should be somewhat flexible, such as juniper or mulberry. You can even use a shaft of bamboo or cane but take care that it is not too thick. For that, you can use young bamboo which is strong as well as flexible. Green wood (living wood that you cut from a tree or sapling) can be used if absolutely necessary but should be avoided because it does not provide the same power as dry wood. Every piece of wood will have a natural curve, no matter how slight.  As you construct the bow, this curve will determine where you place its main features. To find the curve, place your wood on the ground, with one hand holding it in place at the top. With your other hand, press lightly against its middle. It will swivel so that its natural belly faces you, and its back faces out. These parts are essential to the shaping process. To find the handhold, make marks three inches above and below the center point of the bow. Anything within these marks is the handhold, above them is the upper limb, and below is the lower limb. Place the bottom end of the bow on your foot, and one hand atop the bow. With your other hand, press outward, the belly facing you. Use this exercise to catalog where the bow is flexible and where it is not. Using a knife or similar tool, shave wood off the unyielding spots on the belly only, until both the upper and lower limbs curve similarly to each other. Check your progress frequently. When both limbs are more flexible and are mirror images of each other in curve and diameter, you are ready for the next step.  You want the bow to be strongest (thickest) at the handhold. Be careful to...

TL;DR in Indonesian:
Pilih sepotong kayu yang panjang untuk busur. Tentukan lengkung alami tongkat kayu tersebut. Tentukan pegangan dan belahan busurnya. Bentuklah busurnya. Buatlah takik untuk menempatkan tali busur. Pilih tali busurnya. Pasang talinya pada busur. Tekuk busurnya.