I made my own Baby K'tan type carrier!
Here's what I did:
1. Using a soft measuring tape, measure from the tip of your shoulder to your side just under your ribs. Double this measurement and add 2" for a seam and 2" for shrinkage.
2. Go to Joanns/Hancocks and buy a stretchy fabric of your choice. Don't go for 100% polyester unless you want to be really hot really fast. Also, don't buy something that's super stretchy. You want almost no stretch along the length and a moderate amount of stretch across the fabric. I love their 60% cotton/40% polyester interlock. Go for something that's 60" across too. This will give you enough for the two rings and the support sash.
3. Cut into 3 - 20" pieces along the length. You should end up with three pieces of fabric 20" wide (stretchy) and your measurement from #1 long (non-stretchy). You will have a scrap piece if you bought 3 yards for making the long sash. Prewash (and tumble dry!)
4. Take one piece and sew it together along the short ends with a French seam (gonna have to look that one up, don't have the room to explain it). Repeat with a second piece. The loops are done (unless you want to hem the sides- I didn't). I didn't make the smaller connecting loop because the ktan is actually easier to use without it. Go see babyktan.com to see the smaller loop. She's right, you don't need it.
5. Now the support sash. This uses the third piece. It isn't going to be long enough to tie in the back, so you need to either sew on some fabric to the ends to extend it enough to tie (I used a piece of an old Tshirt in a different color for an accent color. I cut the pieces so my accent fabric would be in the center.) or do what I did: Buy two rings like you would use for a ring sling and sew them onto one end (just like for a ring sling). You use it just like normal except that instead of tying in the back, you thread the free end into the rings like a ring sling.
I want to add an additional note regarding the sash: In the photos you see my sash tied in the back, but it will stay put much better if you make the sash longer---long enough to criss-cross in the back, bring it around to the front, and then tie it at your belly. That is why I have give the measurement of approximately 9 ft (3 yds) long to fit most.
6. Download the instructions and start wrapping.