The construction also prevents the batteries from rattling around in the Altoids tin.
Capacity is about 14 batteries.
I didn't document this during construction, so let me know what you think about the step-by-step drawings.
Step 1: Materials and Serging
A, as thin as possible, 2" by 18". I used a piece of DWR nylon that I scavenged from a broken umbrella (that's why it's pink). Besides being a found material, this had the advantage of already having a fraying-preventing seam sewed along one edge. If you don't have that much luck, simply sew a zig-zag stitch half on, half off the fabric, as demonstrated in the illustration. (If you have a serger, feel free to use that instead.)
B, somewhat thicker and stiffer, 2.375" by at least 7". I used a piece of slightly stretchy broadcloth, I think. Serge the edges (top, right, and bottom only) if you'd like.
Step 2: Starting Assembly
The top of cloth A should be 1/2" below the top of cloth B, and the bottom of cloth A should extend about 1/8" below the bottom of cloth B.
Step 3: Making the Loops
- Measuring from the last line of stitching, make a mark 0.4" (the diameter of the battery) along cloth B.
- Measuring from the last line of stitching, make a mark 1.03" ([Pi/2+1] times the diameter) along cloth A.
- Line up those two marks, and make a line of stitching vertically down the length of the fabric. Start this line of stitching a bit above the top edge of cloth A, and terminate it approximately at the bottom edge of cloth B. Remember to make the ends of this stitching secure by backstitching.
Step 4: Finishing
Trim the bottom of cloth A so that it is flush with tho bottom of cloth B, and secure the two together with a zigzag stitch made half on, half off the fabric.
Serge the right hand side of cloth B so that it extends about 3/8"-1/2" past the leftmost extent of cloth A. (this isn't critical)
Finish the cloth liner by hand-stitching the strip into a torus, overlapping the edges about 1/8".
The project is now ready to fill with batteries. You'll need to put the cloth toroid in an Altoids tin to prevent the batteries from falling out of their pockets, and you'll find that, with a bunch of batteries in stock, the tin will close best if the hand-stitched gap in the belt is at the right or left-hand side of the tin.