How to Make a Klein Bottle

One tricky part about using the clear vinyl tubing was that it got kinks in it if it was bent too far. You need to find a sweet spot between having the tube too long and having it too short in order for it to not get a kink in it.

First, cut a small 1 inch section off the end of your vinyl tube. You’ll make this into a template for the hole on the side of the bottle. Put your bottle on a table and bend the tube into its final position above the bottle. It’s possible to use a shadow to help you with alignment. (You’re probably using two hands to bend the tubing into shape, so either memorize the location of the intersection of the clear vinyl tube and the wall of the bottle, or get a friend to help you with lining the 1″ slice of tubing up above the intersection, and using the marker to draw a line that follows the edge of the bottle.) mark the height on the bottle where the tubing crosses it. look at the first picture for an example of this piece.
If you’re short-handed and have to memorize the position of the intersection, drop the tube and then place the 1″ section where you remember the intersection to be, and mark a rough line on the slice of tubing where the edge of the bottle The pictures might be the best representation of this. It isn’t critical that this is perfect, but you should get a good general idea of the placing and angle.
This is necessary so that you have an accurate template for the positioning and size of the hole on the side of the bottle. If it is too high or too low, the tube could easily get kinked or the finished product might be really hard to fill. It’s important to get the angle correct so that the hole you cut will fit the tubing and accommodate its angle. If you have a heat gun or way of directing heat at the tube in order to help it bend and stay in place without kinking, just make a curve that looks good! Ideally the tube on mine would’ve been shorter, but I was limited by the integrity of the tube as a circle.
Mark the tube on the top and bottom where it should connect to the bottle during this step, because you’ll already have the tube in the position you like. Note that if your tube is going to go over or under the threads on the bottle, the mark should not go at the point of contact, but at the end of the threaded portion.

for the top connector, If the tube does not fit on the inside or outside of the top of the bottles threads, you need to either sand the threads off or cut the entire threaded portion off. If you’re using a very cylindrical bottle where the threaded portion is much smaller than the of the bottle itself, you need to keep the threaded section on and work around it, possibly by whittling your tubing down.
On the bottom of your bottle, trace a circle with the slightly smaller outside diameter as your tubing.