https://goo.gl/rU9sy0 - Templates
HERE are the answers on some of the questions you've been asking me!

What I'm using this for? Target shooting only.

Can I use this for hunting? It's not meant to be a hunting weapon,I think it's capable of taking down some small animals like rats or something, but since I'm not hunter I didn't even think about that!

What the string is made out of? The string is made out of fishing string. I'll make tutorial for that as well!

What the bow arms are made out of? It's made out of regular hand saw blade for wood, it's pretty cheap, it cost me less than 1$ to make bow limbs for 2 crossbows!

What the riser is made out of? It's made out of 2mm inox plate, you can use mild steel, but since inox plates are just a bit tougher I used that!

Which material you used to make the trigger mechanism and is that small spring necessary? I used 2mm mild steel plate, it't not necessary but without that spring you'd have push the trigger manually every time you cock the crossbow!

How thick are the pulleys? 1/8 of an inch.

Which wood I can use to make the stock? Since there is no big pressure on the stock, you can use pretty much any type of wood. I used natural hard wood, but you can you plywood as well!