The reason for using several small magnets instead of 1 big 1 is that the way you put them together increases their strength (or so the DIY site I found to do this says). You alternate the poles and doing that supposedly creates a stronger pull where they join.
The neodymium magnets are strong little suckers even so. Craig and I both were really surprised when they came at how strong they were. I had to work with them in short stints because my fingers got tired trying to pry them apart. You have to slide them apart and it can be a major PITA when you get down to 3 or 4, so I started with a long block of them and added magnets as I went until I used them up. I put them at the edge of the deep freeze and slid the last few apart that way. Be very careful with scissors or knives around them, especially when they are in a big block before you start separating them.
Okay, to put them together, you will need 4 for the 4-oz jars and 2 for the 1.5-oz jars. You will be forming a 3/4 x 3/4 x 1/8 D square of magnets for the 4-oz jars and a 3/4 long x 3/8 wide x 1/8 D block for the 1.5-oz jar.
Hold 1 magnet flat (the 3/8 sides) between your thumb and forefinger of each hand. KEEPING AT LEAST 1 finger between them, check for the polarity. Trust me, you will feel the push or pull even through 2 fingers. You want them to repel. Turn 1 sideways and let them click together on the 1/8 side. Now, hold them so that both are covered with your thumb and pick up another single magnet with your other hand. Check for the push/pull (again, you want the push/repel), then let it click on at a 90-degree angle so you start to form your square. Do the same for your fourth magnet to make the square.
Make sure you keep at least 1 finger between them when you are putting them together. I learned that the hard way and had to mess with taking them apart too many times.
You need to seal them in something to create a moisture barrier. The easiest way to do that is to wrap them in clear shipping tape. Everyone who has ever taped up a package for shipping knows how well it sticks to itself. Trim as needed. Then stick them inside the jar lid.
We already had a label maker so I just got some black ink on clear tape and made the labels as I filled the jars.
I did this in assembly line fashion. I did anywhere from 10 at a time to 5 when fingers were getting tired. Put the magnets together, then wrapped with the shipping tape, stuck the magnets in the lids, pulled the old spice jars out I was going to empty, made labels, stuck to bottom of jar, and then filled. Make sure you put the label on the bottom before you fill the jar, it's just easier.
I'll take a picture and post it later of a finished lid. I'm going to have to find another photo hosting place again as Amazon is apparently just storage and only lets you have temporary links.
Nope. 
