Okay, this is a simple tree swing which is really easy to build, even if you don't have any hardware tool at home like me.
Step 1: What's the Plan?
Step 2: Get the Materials
Manila rope is very durable and is usually used for fishing net and scouting rope. Chengal is a kind of hardwood tree found in Southeast Asia, especially in Malaysia, Singapore and Thailand. This is the wikipedia entry about chengal tree in Malay. Can't find one in English. May be you can use Google Translate if you wish to read it.
Besides helping me to cut the chengal plank into the size I want (Dimension = 24" x 10" x 1 5/8"), they also helped me to drill the 4 holes (Diameter = 6/8") at the corners of the wood for the rope to pass through.
So at the end of my hardware shopping trip, I got these:
1. chengal wood = 24" x 10" x 1 5/8" (which is surface finished & drilled)
2. braided manila rope = 1kg (for 8 ft. tall branch)
Step 3: Put on the Seat
When the length is confirmed, cut the manila rope using a pen-knife. I'm surprised by how easy it is to cut it.
Then do the same to the other side of the swing rope.
Step 4: Put on the Seat (wood)
Tie knots at all the ends of the rope at the desired height - mine is 20" above the ground.