Today I was helping out a fellow cloth diaper-sewing mom and showed her how I always just did my inserts before. However, she told me of a method that she had read about that, while it may have an extra step or two, is probably easier to get a cleaner final product out of for most people. ;)
So, here is an adaptation on the method she told me about using some scraps I had laying out in my sewing room.
For this example, I used a scrap of "Zorb2," 4 layers of hemp jersey, and a "stay-dry" wicking jersey outside fabric. You can really use anything absorbent though, and you don't need any stay-dry layers unless you want them. I typically only do my top face stay-dry if anything at all. You can use terry cloth (upcycled old towels or washcloths), microfiber terry, cotton sweatshirt fleece, cotton jersey, knit, or interlock (upcycled T-shirts), bamboo, cotton, or hemp fleeces or sherpa... Really, there are SOOOO many options for inserts. The absorbency of the materials you choose will dictate the total number of layers you should use. I don't recommend making inserts too thick though, because they'll take longer to wash and dry and not come clean as easily (hold residues and get build-up). I prefer doing multiple thinner petal-style inserts, or an insert and matching smaller/thinner doubler. You can also do two thin inserts and sew them together on just the ends or one end so they wash and dry more easily but still stay attached. :)
Start by cutting the absorbent inner fabric layers to the size and shape you want your finished insert to be. Then, cut two pieces of the fabric for the outside of the insert 1/2" bigger than the inside pieces all the way around.
Here are some examples of different inside absorbent materials laid over the larger outer fabric:
Here I have hemp jersey pinned onto wicking jersey:
Use a wide large zig-zag stitch and sew around the very edge of your absorbent (Zorb 2 here) material:
Prepare 2 faces and then pin them together with their outside-facing sides facing in/together:
Next, use a straight stitch and sew just outside the absorbent layers when sewing them together:
Leave a turning hole on one end, and then trim your corners:
Turn right-side-in through your turning hole:
IF you will be using the insert as a snap-in soaker, apply your snap(s) now:
Nice hidden cap(s) with padding both above and below:
Close up your turning hole:
View of the under-side with the snap stud:
Ignore my messy top-stitching...