This step is totally optional but I chose to lightly quilt my charm pack squares onto batting of the same size. I just did straight-line quilting.
Sew the 4 squares for your sides in a row with a 1/4 seam allowance. For the two side ‘arms’ of your ‘t’ attach the remaining squares by sewing from seam to seam.
Now with your fabric right sides to right sides start sewing together sides that are closest to each other.
Lastly, all you need to do is close that turning gap. Fold the raw edges inside the cube and use clips or pins to hold the folded edges together.