Muslin Grid
Instead of drawing a grid on the interfacing, or using interfacing with a grid already on it, I made a reusable grid that I can lay under the (translucent) interfacing while I’m arranging the tiny squares.
For this, you’ll need a piece of muslin or other solid scrap fabric at least 21” x 21”. Press this fabric, using starch or Best Press if you have it, until it is completely flat and free from wrinkles.
Lay the pressed fabric on your 24” x 36” cutting mat and use a permanent fabric marker and the lines on the mat as a guide to draw a 20” x 20” grid made of 100 squares, each 2” x 2”.
If you’re planning a checkerboard design with two color groups (like my blocks) mark an “X” in every other square. This will make it easy to keep track of which color goes where.
I used a Copic marker to draw my lines. If you don’t have a permanent fabric marker, a Sharpie will also work, but it may be fume-y during the block making process. The marker will probably get on the ruler so, if you have a metal drafting ruler or an older quilting ruler, use that instead of your good 6” x 24” ruler. Before using any marker on top of your good cutting mat, test in an inconspicuous place to make sure no bleeding will occur.
Pressing Board
You’ll need a flat, sturdy pressing area at least as big as your muslin grid. Ideally, this would be a pressing table or board made of plywood wrapped in batting and fabric.
If you’re looking for something a little simpler, you can just lay a couple of layers of cotton batting on your work table. (You’ll be pressing on this surface, so be mindful of whether this will damage the table.)
Small Scissors
Cutting the seam allowance open is probably the least fun part of this process, but it’s a lot easier with the right scissors! I found that my dressmaker’s shears were too big to open the seams efficiently. For the blocks shown in these posts, I used 5” paper cutting scissors. Their super-sharp point slid into the seam allowance easily, and the handles were relatively comfortable to hold (which is important, because there’s a lot of cutting to do). If I were making the blocks today, I would probably use my Kai Embroidery Scissors.