This instructable will teach you how to make a small container from two bottle caps and a bottle neck. It's a great way to re-use bottles that you may have been throwing out.

I just wanted to acknowledge that this is not a completely original design. I got the idea from the Groundspeak forums, especially the user "Odie442". However, there is no existing instructable, and I'm sure that everyone will appreciate it. The pictures and text are all original though.

The container can be used as a micro geocache. If you don't know what geocaching is, check out www.geocaching.com or one of the many instructables here that can teach you what it's all about.

Besides that, these could be maracas, fishing bobbers, boxes to hold small beads, game pieces... anything you can think of! Just don't bother doing steps 4-9 if you don't want it to be a geocache.

Step 1: Materials

To make the basic container, you will need:

1. A plastic soda bottle with cap
2. Another soda bottle cap (short, mine is from a coke)
3. Scissors

To make it into a geocache, you will need on top of that:

4. A dark permanent marker
5. A pencil
6. A hot glue gun, with glue stick
7. A fine toothed saw
8. A sheet of paper

Also, other bottles, adhesives, cutting materials, etc. can be used. People have a lot of success with 1/2 L water bottles as well as gatorade bottles. Tyvek can be used in place of paper for a waterproof log scroll. However, this is all I had at the time.

Step 2: Cutting It Out

The first step to cutting the neck off the bottle is to pierce through the side.

Then, cut a loose circle around the neck, as in picture 2. Be sure to recycle the big bottle section left.

Next, cut the bottle right at the point it begins to flare out, as in picture 3.

The piece should have a ring of straight plastic coming off of the threaded top, with a relatively smooth edge, as in the last picture.

Step 3: Combining the Top and Bottom

Now we are going to put the short cap on to the plastic part you just cut out. I tried to put on a larger cap, similar to the one on the top of the bottle, but it did not stay on as well as this one did. Place the cap loosely on top of the upper piece.

To get the pieces together, put it under your foot, with the small cap on the bottom. In picture two, I was slowly putting weight on my heel. You do not have to stamp down on it. After hearing two clicks, the cap is snapped on.

The result is a cap snapped on to the neck of another cap. Picture three shows you how tight it should be. At this point, the container is pretty much done.

Step 4: Weatherproofing

As an extra layer of defense against moisture, I used hot glue. Plug in your hot glue gun to get started.

Pipe a stream of hot glue around the seam between the small cap and the plastic of the top. Try and have it in a straight, even line around the container. Avoid large blobs of glue by rotating the container in your fingers at a steady pace.

Now you will have a container that will better keep out water, dirt, etc.

Step 5: Alternate Weatherproofing

Other people have suggested that pvc cement, crazy glue, or the adhesive "Lexel" will do a better job. Instead of merely coating the plastic, they will fuse the two pieces together, creating a truly watertight seal at least on the bottom.

Hot glue has worked fine for me, and it was the only thing I had so its perfect. One suggestion though would be to apply it before crushing the pieces together so it really gets in the seam.

Step 6: Labeling

Label the container so people know which side to open, in which direction, and that they have found a geocache. The top, with the big cap that screws off, label "OPEN". Draw clear arrows to show them which way to twist.

On the small cap, write "GEO" to show that it is a geocache.

Step 7: Mini Pencil

No ordinary pencil will fit in this small container, but it is still useful to have one. First, measure the pencil, and mark where to cut it with the sharpie.

Next, saw off the tip at the sharpie mark. Because it is so small, I just pulled backwards on the saw around the pencil, then snapped it off.

This will become the pencil people can sign the log with.

Step 8: Log Scroll

You need a log book for the geocachers to sign. Measure the height of the container, and mark it on the paper.

Fold the paper over on that mark, then cut down the fold. Then, you will have a slip of paper the correct size to be rolled up in the container. If you want more room, consider making two or three of these and stapling them together.

Finally, label the log as in picture 3. Make sure to include instructions, the label "LOG", and a spot for the FTF (First To Find) to sign. A cache note would be good to include too.

Step 9: Final Product

Assemble the geocache by rolling up the paper inside, putting in the little pencil, then close it up.

All you have to do is go hide it! Make a bunch for a multi-cache, or just publish one. Be creative and see how you can camouflage it.

Step 10: Om Nom Nom

Also makes a delicious snack.

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Please post photos with your own creations. What else can you use these for? How did you hide/camouflage it?

Be sure to comment / rate too! This was my first instructable.