You can just sew through the odango itself (it's just foam and wig fiber). It would probably work for that small an odango, although if it were me, I'd make a mini stub anyway. I did it for this Shampoo wig, for example: http://www.cosplay.com/photo/2921898/

Make a mini stub to anchor the odango to, and sew in more wefts around the stub so you don't see the hair being pulled up. Small, lightweight pieces can also be sewn directly to the undermesh without warping the wig, bit heavy pieces need some sort of stub or superstructure to better distribute the weight.

SilverInsanity replied on 02-08-2012 at 04:40 PM: 1.) How lightweight is lightweight? 2.) if it is light enough, sewing felt to the bottom after making the odango would be the best option? Ref: http://fc09.deviantart.net/fs70/i/2011/024/c/0/konan_by_nagato392-d35wuwf.jpg

What about a character that defied all laws of the known universe and had an odango but hair wasn't pulled up into it. How could you attach it to the wig then?

I don't think so. Backcombing (to turn your pigtails into fuzzy balls) would probably be more effective on human hair. You could probably make odango with foamcore and extensions and attach them to your own hair, however.

Quick question, is there a way to do this with foam but on the human hair? I just didn't know what I would use. Any ideas?