Canning jars, also known as Mason jars, are traditionally used to preserve food but have many other uses. People have found literally hundreds of uses for them, from storage of dry goods and small parts to crafts, gardening, and other applications. A 3D Printer can be used to extend their functionality even further.
I released some of these some time ago, intending to get a few more done and do this post, but I got sidetracked and it took a while to come back. Hopefully you'll find these valuable.
These plastic lids sold in many stores (and obviously online) are great for capping-off home canned goods for the refrigerator after they've been opened, or for making freezer jams, making and storing extracts (like this homemade vanilla extract), or any other application that requires a lid… pretty basic.
The commercial lids are great, but could be improved upon; that's what I set out to do. My version, pictured below has facets around the outside, giving a surface that is easier to grip and easier to turn. The seal is also at least as strong as the commercial lids, and can be seen here keeping the water in the jar even when inverted.
As thingiverse user DrewTM points out in the description for his canning jar lid, parafin wax can also be used to create a tighter seal. This works especially well in our lid because of the ring on the inside of the lid, which gives a nice channel for the parafin to flow into for a seal.
Remember, these aren't for actual canning. You cannot properly process or seal a jar with this lid. These lids are only for storage in the refrigerator or freezer, or the storage of dry foods or non-food items.
I've released these canning jar lids in both regular and wide mouth versions as a thing on Thingiverse.
Here is the same lid, with a slot added to function as a coin bank. You can get the same thing by punching a slot in a regular metal canning lid, but this looks a little nicer and is just cooler. The bank lid can also double as a sharps container for razor blades in the shop or bathroom.
The bank lids for canning jars have also been released on Thingiverse.
Fruit flies bothering you? Just print this out, put some fruit, juice, or syrup in a jar with this lid on top and you're set. The flies come in through the hole but can't figure out how to escape. You'll want to clean it out every couple of days to keep them from breeding effectively in the trap.
This too is available via thingiverse!
Modeled somewhat after this lid, the sprouting lid is used to strain water off of sprouts and seeds.
This one stopped me up for a good while. I had worked on a few approaches for getting the straining mesh right, but just hadn't gotten it to work well. I had an approach in mind, but hadn't gotten around to implementing it. Thingiverse user Wauter did implement it though, and really well at that. Bringing in Wauter's work as a library made the implementation of this sprouting lid very quick and easy.
Wauter's mesh library will probably prove to have much farther reaching applications. We have another design we're working on right now that uses this mesh for a very different purpose. We'll have a post out featuring that soon.
To sprout seeds with this lid, just put your sprouting seeds in the jar, screw on the sprouting lid, add some lukewarm water, and soak for about 8 hours. After soaking, drain off the water through the lid, rinse the seeds with some fresh water in the same manner. Rinse once or (preferably) twice a day with cool or lukewarm water, and in a few days (the time will depend on the type and freshness of the seeds you're sprouting, and on the temperature of the room they're in) you should have sprouts.
After the sprouts have grown, but before they start producing branching roots, refrigerate the whole jar to slow their growth; when refrigerated, rinse the seeds every two days or so. They'll keep for a while.
Use only seeds that are sold for sprouting, so you know they haven't been treated for garden use. Recommended seeds are alfalfa, radish, clover, mustard, cabbage, sunflower, and mung beans (for bean sprouts).
See this thing on Thingiverse for more usage and printing instructions.
Need to strain the juice off of home canned fruit or vegetables? Want to strain the grains from your fresh batch of kefir? Inspired by Strainer for Mason Jar by Thingiverse user ojaybe, this lid strains large pieces from liquid.
You can also use this as a shaker lid, for finely shredded cheese, etc.
Download the straining lid on Thingiverse.
This lid uses water to form an air trap that will let carbon dioxide and other gasses vent off of fermenting foods, while not letting in the oxygen that would spoil them.
Some ideas for fermented foods this could be used for include sauerkraut, kimchi, ginger beer, or pickled vegetables (garlic, carrots, peppers, etc). Fermented foods are healthy, easy to prepare, and taste delicious.
The air trap is all one piece, and I believe its geometry can only be built with additive manufacturing, such as on a 3D Printer.
To use it, just put it on your jar, and fill the reservoir on top about half full of water. If you under-fill it, it won't do anything, and if you over-fill it you'll get water leaking down into your jar (though this shouldn't hurt the food, so it probably wouldn't be much of a problem).
For some recipes for fermented foods, check out pickl-it.com/blog/recipes/. Some of the recipes are a bit out there, but some of them are pretty standard, tasty fare. There are many other places to find recipes to find recipes too; I picked this one because the recipes are targeted towards small (canning jar sized) batches.
You can download this from Thingiverse.
In addition to the designs featured here and those mentioned throughout the post, here are a couple of other cool things to check out.
This sippy lid by Thingiverse user chowderhead is a fantastic idea. Great for kids, or even for on-the-go grown-ups.
This canning funnel by Thingiverse user cruezerm requires some special printer settings, but looks quite useful!
Bonus: Can Strainer
The other day I saw a can colander in the canned vegetable section in the grocery store. My first thought was, "Huh, that could be handy," immediately followed by, "I could print that." And so I did.
It's not really as related to home canning or canning jars, but for store bought jars of fruit and vegetables, here is a handy can Colander/Strainer.
Print this, then use it to strain your canned goods by pressing it into the top of the open can. This design allows you to apply some pressure to squeeze the food to help drain it.
The model here was made for a specialty can, but the openSCAD file can be modified to allow you to make one to work with any size can.
Like everything else here, you can download the can colander and its source files on Thingiverse.
Does anyone have any ideas for other canning jar accessories they'd like to see made? Let us know!