Mei Tais are very simple to make a there are a host of tutorials and instructions available on the web. I looked at a few and combined a lot of the features I liked best in the simplest Mei Tai styles. It's basically a rectangle (roughly 16x20 inches) with very long straps (60" on mine) made of double, triple, or even quadruple layers of some sort of durable but soft fabric with minimal stretch (I used a suit weight silk that I bought before I was pregnant but never used) and double or triple seams with high quality thread every where for strength. If you are very short, slender, or do use wrapping styles that require going around the waist or back twice, you can get away with shorter straps.
I'm not sure if it's my bad back, but it wasn't as comfortable as I had hoped it would be. I will try making one more in the near future and seeing if any of the modifications I have in mind help. I would definitely recommend making very wide shoulder straps (6" or more) and padding with an internal layer of quilt batting or thick fleece. My straps are about 5" and cut into my shoulders after a few minutes. I did put some padding in the main body to make it more comfy for my son, but he doesn't seem to notice it. I think I will use a cushier material for the seat pad in my next Mei Tai. Also, if you think you'll be using it a lot or have a baby who falls asleep easily, I would say to try one of the patterns that includes a sleeper hood.
Baby's verdict: He's hot natured and sometimes gets a bit over heated even though it's made out of silk and cotton. He's also in a wiggly stage and gets tired of being in it when he's in an active mood. When he's tired, he has no problem falling asleep in it but would probably stay asleep longer with a hood for keeping his head positioned. He would prefer a higher seat that allows him to nuzzle my shoulder.
Making one and using it has given me a much clearer idea of what my unique needs and wants are in a carrier, so I have some interesting plans for my next Mei Tai. When I finish it, I'll be putting up the pattern so you can make your own if you like what you see!
For anyone making a Mei Tai for the first time, here's a tip: this project will take much longer than you think it will for just being a rectangle with straps. It took about 4 hours of sewing not including the cutting and prepping. The double stitching and reinforcing take a long time. I didn't believe it when I read others saying it, but the straps truly are the most time consuming part of the project.