My pillow remains unfinished for now because it will be easier to pack around
as a teaching aid. After a while, it will be finished and "retire"
gracefully to the sofa. I’ll use the fabric backing option to complete the
pillow: you make the backing of 2 strips that overlap about 1-1/2" in the
center. You can insert a pillow form easily and, more importantly, remove a
pillow form easily when you want to wash the pillow. The math for figuring out
the length and width of each strip is given below (it’s not difficult). Adjust
to meet the needs of your pillow top.
My pillow is 18-1/4" square. Cut 2 pieces of fabric backing 19-1/4"
x 11 ¾". The 19-1/4" is the width of the pillow top plus ½ "
seam allowance on each side (18-1/4 "+ ½" + ½"). The
11-3/4" is arrived at as follows: divide 18-1/4 "by 2. This equals
9-1/8". You want a 1-1/2" overlap: 9-1/8" + 1-1/2" =
10-5/8". Don’t forget the ½" seam allowance on both sides! This
brings you to 11-5/8". I’ve rounded up to 11-3/4" – I’ll eat up
an extra 1/8" on the overlap.
Clean finish one long (19-1/4") side on each strip by turning under and
pressing ¼"; then turn under and press ¼" again. Sew on a sewing
machine with a straight stitch. You’ve enclosed the raw edge. Overlap the
fabric strips, (the 2 clean finished edges overlap in the middle), so you have a
19-1/4" square. Pin the overlap at the side edges to hold in place.
Pin the knit pillow top (18-1/4" square) and the backing square
(19-1/4" square) right sides together. You’ll see ½" of backing
fabric all around. Using your sewing machine, sew the pieces together taking in
a ½" seam allowance on the backing and sewing the pillow top in the rut
between the bound off stitches and the last garter ridge. Use a smaller stitch
at the corners to strengthen and get a good corner. Turn right side out. Insert
pillow form of your choice.

What if you want to make squares facing in different directions? In the
pinwheel swatch above, the square on the lower left was made first. Cast on 10
stitches with orange, then cast on 10 stitches with white. Finish as for a basic
intarsia mitered square. Knit the square in the upper left corner next. Cast on
10 stitches with white, pick up 10 stitches with orange along the top edge of
square 1. Finish as for a basic intarsia mitered square. Next, knit the square
in the lower right corner. This square is done a little differently. Cast on 10
stitches orange, then cast on 10 stitches white. Use a purl 2 together join to
unite square 3 to square 2 (technique detailed below). Turn, continue making the
square as for a basic intarsia mitered square AND, on Right Side rows, continue
joining square 3 to square 2. For the final square, in the top right corner,
pick up 10 stitches white from the top edge of square 3 and pick up 10 stitches
orange from the side edge of square 2. Finish as for a basic intarsia mitered
square.
The example below is worked in strips. I suggest you try this first before
joining squares. Make a garter strip of 10 stitches in yellow using a chain
stitch selvedge on both sides. Work 3-4" (enough to give you a chance to
practise) then bind off all yellow stitches.
1. Cast on 10 stitches with pink. Insert your right needle between the
first yellow chain stitch and the main yellow knitting PURLWAYS. The photo
shows this step being done further up the strip.

2. Bring working pink yarn around needle as if to purl the stitch.

3. Pull new purl stitch through. Pass last cast on stitch (on subsequent
rows, the slipped stitch) over the new purl stitch. The photo shows the new
pink stitch with slipped stitch passed over it.

4. Turn, slip the first pink stitch KNITWAYS and work to the end of the
row. The photo shows the wrong side of the work ; the first pink stitch
being slipped.

5. On subsequent Right Side rows work until one pink stitch remains on
right needle. Bring your yarn forward and slip this last stitch purlways.
Insert your right needle between the next yellow chain and the main yellow
knitting purlways. Continue from Step 2.

Why stop at one corner? The photo shows a 3-cornered intarsia square with a
simple mitered square to finish. Can you see how it’s done? Cast on as for
three 10 stitch x 10 stitch squares (60 stitches). The stitches are grouped as:
10 + 20 + 20 + 10. The 20 stitch groups form longer sides. Miter your corners
just as you did for the basic mitered square module changing colors as desired.
Of course, you can add purl stitches, eyelets, stripes, whatever you like –
drag some yarn out of your stash and play!