I have pieced batting pieces by using the stitch that goes back and forth between the two pieces; it's something other than zig zag on DSM; can't remember what it is called. Another method that does a nice job is using the flatlocking stitch on the serger. Then there is the new fusible batting tape, too.

I do this all the time too. What I do is lay the edge of one piece of batting over another, then cut through both with my rotary cutter. This gives you two edges that are exactly alike, can be butted together easily and can be joined using a multiple-step zig-zag across the seam.

I pieced together batting left overs (I think it was polyester too and I usually hate that) for the Diamonds quilt I just did. At least I used it all up!

Waste not, want not. Saving those pieces of batting and sewing them together only makes sense! No one will ever know the difference - and even if they do the batting is serving the purpose it is intended to serve.

Cutting the two pieces together gives them the exact same lines to butt up against each other. You don't need to cut off very much at all. Baste them together sewing one way, then back the other to reinforce. Depending on your quilting, you won't need small stitches.

It always fascinates me how those pieces can really add up! I use the wide zig zag , and long stitches .

I always try to purchase the same batting so I can use the scraps and but them together to create new batting.

I've done this several times usually on lap size quilts. My really small pieces I use on rag quilts.

I don't even bother to sew them together. I think this technique works best with longarm frames, but I simply lay the second piece of batting next to the first, on top of the backing. The quilting holds it all together.

Much prefer to ladder stitch my pieces. Some which I feel are too small go into a bag and wait for the next dog cushion and go in there. The dogs love them even playing if they get the chance, tug of war can last a long time.