Please note: This pattern is intended to enable babywearers to make my bags for themselves or their friends and family, absolutely not for sale. I put a lot of time and effort into coming up with this design, which as far as I know is completely new, so I'll be pretty heartbroken if I find that somebody has pinched it!
I am making the design available for free because we are a small community and I think it is nice if we help each other out - please use the pattern in the same spirit. All measurements are in centimeters.

Onbag DIY Pattern by Sarah Dickinson is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License.
Onbag DIY Pattern (PDF Format) 1.89MB [version 20081008]
Also see our DIY Kits section, where you can order a hard-copy of these instructions plus some extra goodies to finish your bag in style!
The tutorial also includes a section on adapting the basic pattern to make the smaller Onbag Baby, the Accessories and some other ideas...
You will need:
Outer fabric (medium weight cotton drill works well):
Lining:
These instructions are still quite new and relatively untested so be careful before you cut (!) and let me know where the pitfalls are!
I would love to see photos of your DIY bags - and post them here if I may!?
Be warned that you'll find yourself sewing through quite a few layers at times - go slowly.
For some inspiration look here for some other mama's DIY Onbags.
You may also find this discussion on The Babywearer DIY forum useful.