Watertight Roundbox using Soda Bottle Cap (PCO1810)

Here I am sharing some roudboxes which re-use soda bottle caps. They are designed to work with the most popular soda bottle caps and with those caps, the roundboxes will be watertight.

The idea starts from a little roundbox project. As many of you know, the roundbox is a popular project for beginners who just start to learn 3D design. I made my first roundbox and printed it out. Then I realized I could just make it longer and use it to store a mask - during this pandemic time it is always a good idea to keep a spare mask with you. And then, one day, when I was holding a mask box and a bottle of Soda, I realized I could modify the thread of the mask box so I can re-use the soda bottle cap. A simple screw-on cap for the roundbox is not watertight. But soda bottles are watertight. So if I can re-use the soda bottle caps, the roundbox could be watertight as well. Plus, reusing is always better than recycling. So after some fails and tweaks, I got it. I tested with the caps of Coca-cola and Pepsi. Their caps have different designs. Coca-cola's caps are easier to work with. They are flat inside with a layer of soft rubber-like material to seal the bottle. Pepsi's caps are more complicated. Their caps have some kind of groove pattern that is supposed to "squeeze" against the wall of the bottleneck to seal it. So it is critical to get the size and thickness of the bottleneck right... Nevertheless, I have figured it all out. They both work on the roundbox. I tested by filling the roundbox with water and checking if it leaks. It seals fine.

I created the stl files of the roundbox with different heights and surface patterns. The file names follow this pattern:
roundbox_aaamm_B.stl

Here aaa is the heigh of the roundbox without counting the threaded part. B could be one of the three letters: S = smooth surface, L = line pattern and K = knurling pattern. For example, roundbox_80mm_S.stl is the one I printed the most. It is about 95mm tall (80mm + the height of the cap) with a smooth surface. This length is perfect for storing a mask. Just fold the mask in half, and roll it relatively tight. It fitted perfectly in the box. Folding will not affect the usage of the mask because you will pinch the middle of the mask anyway when you wear it. You can rest for sure that your mask will stay in the box nice and clear. If you drop it, you can just pick it up, wipe it or even rinse it. It is watertight, your mask will be clear and dry.
You can also use it to store wet wipes if you want. But the wipes are soft and could slide down into the bottle. Then it would be hard to get it out. If you really want to carry wipes, I would suggest that you buy an on-the-go package.

I like to print it with black PLA. Let's keep it lowkey, shall we?

The 20mm box is cute, especially when it is printed in white and paired with colorful caps. Apparently, I am not the only person who thinks that way. I do notice this design: https://www.thingiverse.com/thing:4900080 But I can claim that the design is not watertight LOL.

The 40mm roundbox is tall enough to hold a match. The 60mm version can hold a Qtip. So, maybe you can create an essential kit for camping with some imagination.

The 160mm version is for those people who MUST store their mask without folding... but OK with rolling :)

Keeping on doubling the length gives us the 320mm version. Nah, I can not add a pattern to it as my laptop began to complain out of memory... Anyway, I don't have a plan for it either. Maybe you can use it to store coins? But the bottle can not accept the quarters. That is a bummer. However, it can hold pennies, nickels, and dimes. According to my calculation, it should be able to hold at least 300 dimes. Not too bad as a piggy bank.

The 640mm version is not a joke. It is a troll... If you are lucky enough to have the access to a 3D printer that is capable to print it, and also crazy enough to print one, please do share a picture!

By the way, I did not work on a cap for the roundbox. If you need one, just enjoy a soda with the cap of the right color. No no no, I totally don't see a problem with it. LOL.

Happy printing!

I mostly printed with 0.16mm precision but it is not critical. Lower precisions up to 0.3mm should work as well. No support is needed.