Prism99

I definitely think you could machine quilt this on a domestic machine. Easiest would be to use a walking foot and simply sew straight lines. I would do this by starting at the top middle area and working down from the top, turning as necessary, to quilt in straight lines from top to bottom. My second line would be going from one side to another. Obviously these are not going to be straight lines, but rather straight lines with corners. Once you have that basic + of quilting lines through the middle, you can work from the middle out in each direction. The middle lines are the hardest; after that it gets easier and easier. You would have to quilt some "connecting" lines here and there at the end.

I think one of the problems with trying to FMQ a t-shirt quilt is that it is hard to manage that much bulk plus some sewing machines will skip stitches from the changes in direction and pressure.

Alternatively, you could machine tie. Look for a stitch similar to a zigzag but that stitches in place on one or both sides. Those stitches keep the tie from unravelling. You do not cut threads between ties; rather, you wait until you have a line of ties before cutting the threads close. When I have tried this, I have not really been happy with the look, so I would try the walking foot first.

I'm not sure I would be concerned about the 10" squares drooping without additional quilting. This could be a problem if you were using batting, as it can pull away from the stitching lines and bunch up when quilting is that far apart. I would just quilt around all the squares and see how it holds up. If drooping inside the 10" squares becomes a problem over time, then I would go back and add some outline quilting inside those squares. However, I doubt that you will need to do that.