I like working with fabric pieces which are not square. I like piecing three fabrics together into a wonky block, making lots of those and creating a wall art quilt. These approaches to mosaic art quilts are the most unstructured and challenging from both a design and a piecing standpoint. But even me…..the wonky, non-straight line quilter, likes every now and then to make an art quilt that is a bit more structured. You won’t find repetitive blocks in these quilts but my diagonal pieced mosaics are as structured as I get but even these have some variability.
I just finished two quilts using the diagonal design and sold one in the last two months in this design. In an approach which is very much not like me, I actually cut out pieces from about 200 different fabrics in all different colors/patterns which are the same size. Yes….I start out the same size but make several changes along the way so there is variability in the quilt design. I have used two sizes of fabric pieces: for the larger quilt, shown here in the first picture, I used pieces 2.5″ x 3.5″. 
For the smaller art quilt I used pieces 2″x 3″.
The most fun part of any mosaic quilt is designing it on your design wall. It is a messy process though as you see in the second picture! I often spend several hours placing the pieces on my wall with lots of reorganizing in order for the color transitions to be just the way I want. I’ve done the diagonal quilts two different ways: 1) I place the fabric pieces in fairly neat diagonal rows which build up the wall to create a wall quilt, or 2) I place the fabric pieces diagonally on the design wall but not in any kind of rows, more random but in such a way as to allow me to piece together sections, much like the sewing that occurs in the “3 piece block” design approach. The first picture in this blog is of a diagonal quilt pieced in the second method. The third picture is a purest diagonal piecing in neat rows. In the first picture you can see different size pieces of fabric, some longer, some thinner, some more like squares, some very small. All of those variations are created after the initial colors and pieces are on the wall. There is no right or wrong for any of this. It is just fun to blend the colors and the sizes. For both piecing approaches I like to have piecing lines which vary and don’t match all over the quilt as that moves your eyes here and there with the color rather than the piecing structure.
In the third picture, with the defined diagonal rows, I had fun changing the length of each piece. All these pieces were 2″ to start. My lack of interest in precision of piece size though meant that some of the diagonal rows were more or less than the 1.5″ final width (2″ to start minus two 1/4″ seam allowances) after some trimming to maintain straightness (a necessity for this design), For me, those variations simply add character. Some more narrow rows every now and then are appealing to me…kind of reminds you this is a contemporary quilt and there are no rules!
From a learning and ease of piecing and sewing perspective, making a mosaic art quilt on the diagonal is an easier method than the more random other two methods I use.