The Mei Tai looked to be the best one to replicate, it has no snaps, hooks, etc and it says that it is good for children up to 4 years old. It is just fabric and it ties around you and the baby. Here is the actual brand named one:
and here is how it looks with a bigger kid in it:
Ok, so here is how I made one...
1. Make pattern: I didn't make a head rest or neck support for mine since my kids are big now. If you are wanting to make this for a baby and grow with your child you might need to make the back arch up instead go straight across. Here are my measurements:
This is kind of typical measurements and what I used for the first one I made but for the 2nd, for my oldest daughter, I made the whole thing longer, around 24 inches instead of 20, because I thought it didn't go up high enough on her back.
3. Cut out the padding for the straps (I used quilting batting): I cut out 8 pieces (4 will be stacked together for each shoulder strap) that are 5 inches by 22 inches long. And 4 pieces that are 5 inches by 28 inches long.
4. Cut out body pieces ON FOLD: you will need 3 of them- one for the inside (where the baby sits), one for the outside (that everyone will see) and an inside layer for durability.
5. Assemble the padding: place 4 pieces of the same size together and sew a basting stitch so they stay in place. You should have 3 padding bundles when you are done.
6. Make straps: Fold straps in half, right sides together and sew the length. When done flip them right side out and iron them flat. You should finish with 3 long straps, one for the waist and 2 for the shoulders.
7. Insert the padding: Place the padding in the two shoulder straps about 5 inches from the opening. Place the last bundle of padding in the waist section in the dead center. (I used a safety pin with a string tied to it to pull the padding into the center)
8. Sew the long strips 2 times lengthwise through the center.
9. Layout body pieces like this:
with the straps sticking out the top by 5 inches and right sides of the inside and outside pieces together.
10. Stitch all around the body piece leaving the bottom open: I stitched twice across the straps just for durability.
11. Flip body to right sides out.
12. Tuck in the bottom and sew all around the body piece.
13. Sew the straps inside the body piece: with a square and "x" to help reinforce.
14. Center the waist strap with the center of the body piece and sew a square around the piece.
15. You are done!!