In this instructable I'm going to show you how to cut custom shaped holes into a bottle, using the same cutting method I use in my other instructables. I'm also going to discuss some things to take into consideration when you're planning your design.

I also made a video, which you can watch here: https://youtu.be/Ny8OXoux-U4

Here is what you will need:

Step 1: Prepping for the Cut

When planning your shape it's helpful if part of it follows the curve of the bottle, because then you can use a bottle cutting jig to score the bottle easier. It's also easier to start the crack around the curve of the bottle rather than a flat edge of the bottle.

Step 2: Starting the Crack

To start the crack hold the tip of the soldering iron in one spot for a few seconds, then move it a bit. If the crack hasn't started after a couple inches, stop and heat the score line in the opposite direction. Continue that process, heating each spot slightly longer each time, until the crack starts. Once it does, continue moving the soldering iron in that direction, the crack should follow the tip of the soldering iron as you move it. If it stops moving, try heating the opposite end of the crack. It's helpful to switch things up a bit.

Step 3: Turning the Crack

When you get to the corner, move the soldering iron to follow the path you want the crack to go. If it's not too much of an angle, the crack will follow the tip without much trouble. The same goes for any curves you want the crack to follow. But one thing to be careful of when making sharp turns is a random crack forming. Trying to go around a tight angle or tight curve doesn't always go as planned. Because of that, this method isn't a good idea for small holes.

Step 4: Issue With Corners

Sometimes after you've gone around a corner just fine, a crack will form on it's own at the corner and go away from it. This seems to be from the stresses of heating the bottle, and the corner being the weak point.

Step 5: Finishing the Crack

When you finally do get both ends of the crack close to each other, they usually seem to stop moving completely when they are about 1/8 inch apart from each other. If this is the case, try separating the pieces. If you're cutting a hole, keep in mind that the edges of the crack will be jagged, and this makes it hard to separate the pieces because they are still a bit interlocked. You'll definitely need to tap it loose from the inside of the bottle.

Step 6: All Done!

As you can see, I could have done better following the line I drew on the one side, but other than that this piece came out just fine.

Step 7: Other Cuts I've Made With This Method

I've also used this same method to split a bottle in half length wise, mostly. I was unable to drag the crack into the base of the bottle so I dragged the crack around the base. I also did the same thing to cut a slice off the side of a bottle.

And here is another bottle where I cut a rectangular window out of the bottle. But as you can see, two of the corners have that same crack coming off of them. I've noticed that this happens sometimes with corners, but with most curves this isn't an issue unless it's a tight curve.