I cut nylon tricot iron-on interfacing into strips to use for this purpose. I like it because there is no sign of the 'joining seam 'on the surface of the quilt. The tricot is very thin and soft.

Hobby Lobby has it here

Also Nancy's Notion has it and I think Annie's Catalog does too. I bought the 100yd 1.5" as I use it alot for my cutoff pieces. I try to get it when its on sale if I can too.

I agree with jcrilley. I always use the same technique with the wide/long zig-zag.

The people telling you to use light (non-woven) weight fusible interface are on the right track. This can be purchased on the bolt very inexpensively. Most of the tape on the market is fusible knit product and the thickness, flexibility and cost of knit is not what you want. Also, the knit tapes on the market tend to be too narrow. The tape that is wider and made from thin, stable and low cost non-woven fabric is the tape from Marti Michell.

Batting Together is specifically made for this purpose . . .its sold in a rolled tape form and is handy and works great. I get it on Amazon.

http://www.amazon.com/gp/product/B00...ilpage_o04_s00

I get mine at JoAnn's. I am sure it is availiable online! Love the stuff and save many, many medium batting scraps for use in my quilts.

This is how do it too, works great, ziazag stitch and it is finished.

I recently ordered 2- 15x1.5 inch wide rolls from this site- www.heatressbattingtogether.com. They are located in Northridge, Ca. I haven't used it yet, but will in the near future. I have a lot of scrap batting that I need to use, but most isn't quite wide enough for most projects. I hope it works like I want it to.

JoAnns carries it