I made the prototype for this a few weeks ago after reading this thread about alternative menstrual products https://www.craftster.org/forum/index.php?topic=82588.0
I wanted to address the possible problems with reusing a filling or stuffing of a crocheted outer tampon, so I had a think and this is what I came up with.
EDIT: It's been brought to my attention that the washing and care instructions I had previously were sub optimal. I suggest looking online for instructions on how people care for cloth diapers or cloth menstrual pads.
Here's the pattern I made. Please respect my copyright. I'm happy for anyone to make them for their personal use and/or amusement, but please don't make them to sell. I spent a long time working on the design.
Also I am not a medical professional. I make no guarantee that they won't kill you or make your genitalia unhappy with you. You use them at your own risk and I accept no responsibility for their (mis)use.
I used some Rowan 4 ply cotton I had on hand, but a much better yarn would be be an unbleached 4 ply Hemp. Some sources I know of are http://www.houseofhemp.co.uk/acatalog/Natural.html
which is 100% hemp yarn and http://www.lanaknits.com/usahempton.html
which is a 50% cotton 50% hemp mix. House of Hemp are based in the UK and Lanaknits are based in Canada but both sell worldwide.
Using hemp would make the tampons ultimately compostable and the hemp plant is very good for the ground it's grown in. The yarn when you buy it is often crisp and coarse feeling, but once washed it becomes much softer and more comfortable on the skin, which is fairly important for this pattern
If you'd prefer cotton or are having difficulty finding hemp, them please use an unbleached 4 ply cotton yarn.
4 ply 3 mm hook
Turn and dc (US sc) into 2nd chain from hook through back of chain stitch
Make 26 dc (US sc)
* Turn and chain 1. Make 27 dc (US sc)
Repeat from * for 12 more rows (14 in total)
Make 26 dc (US sc)
In next st make 2 dc (US sc)
Continue making 6 more dc (US sc) down the side of the rectangle, 1 into each row. Turn and make 1 ch
Dec 1st and 2nd st of row, 4 dc (US sc), dec 7th and 8th st, 4 dc (US sc), dec 13th and 14th st. Turn and make 1 ch
Dec in 1st and 2nd st of row, 2 dc (US sc), dec in 5th, 6th and 7th st of row, 2 dc (US sc), dec in 10th and 11th st. Turn and make 1 ch
Dec in 1st and 2nd st or row, 3 dc (US sc), dec in 6th and 7th st. Turn and make 1 ch
Dec in 1st and 2nd st, 1 dc (US sc), dec in 4th and 5th st. Turn and make 1 ch
Dec in 1st, 2nd and 3rd st.
Turn and slip st 5 sts, 1 st per row. Turn and make 1 ch.
Dc (US sc) into each slip st, then continue dc (US sc)1 st per row, down to end of rectangle.
Slip st into the back of each st in the chain cord.
Cut yarn and carefully untie the slip knot at the bottom of the chain. Pull both yarn ends through both chain loops. Pull tightly and trim ends.
To use, tightly roll up the rectangle and tuck it's top end into the little 'hood'. Carefully push up in the bottom of the roll to make it easier for insertion.