How to Make a Thumb Ring (mongolian Archery)

Hi, this is my first instructable and my first try to make a mongolian thumb ring from scrap and with very basic hand tools.
The most important hint from me to you guys: PUT YOUR THUMB IN A PLASTIC BOTTLE! :D If it fits, great, if your thumb is too thick for the bottle, sorry, this one is not for you.

Supplies

Plastic bottle
Hacksaw
Utility knife
File/Sandpaper

Step 1: Cut the Top of the Plastic Bottle

This can be done with a utility knife or with a pair scissors.

Step 2: Cut the Threading

This can be done with a hacksaw. And than do a fine cutting with a utility knife.

Step 3: Cut Diagonally About 4-5mm From the Ring and at About 20 Degrees Angle

This can be done with a hacksaw and then finished with a utility knife when the plastic becomes thinner, the hacksaw will struggle to cut the thin part because it flexes a lot.

Step 4: Almost Done

With the back of the utility knife scrape the burrs and excess plastic parts to make the ring smoother. I don't recommend to smoothen the edges with a lighter (I've done that) because you may bend the thin part that rests on your finger.

Step 5: Make the 'hook'

You should realise and decide by yourself how wide the hook will be, mine is about 20mm. If it's too narrow, the bowstring will rub on your finger, and if it's too wide, it's harder to control the shot. The choice is yours.

This can be done with a sharp utility knife and with precise and strong hands, because it's the most crucial part, the bowstring will rest on it so make sure it's slick and smooth, you don't want to break your bowstring after 3-4 releases.

Step 6: Use a Sandpaper to Finish the Ring

Just to be honest I haven't done this because I'm not even at home, but anyway, I will do it tomorrow I promise :D.

Step 7: Done!

It was nervous and fun at the same time making this ring, needs patiense and a bit of fine hand skills, but when it's done with passion, it's a good prize. I hope you'll like this as my first inateuctable, and I also hope it won't be my last. :) Take care.