There are directions for both circular knitting and flat knitting. I've tried both and the aliens look just the same. Knit with sport weight yarn, they turn out about 1.5" tall. You could knit them with other weight yarn, with appropriate needles, but I'm not sure what size they would be. These knit up super fast, so you can make pocketfuls in just an hour or two!
Materials: small amount of sport weight or DK yarn; pair of 8 mm safety eyes, buttons or yarn to embroider face; stuffing; darning needle.
Knit Circular: 3 mm (US size 2.5) circular needle, knit with magic loop method.
Cast on 20 sts. Join in the round. K 1 round.
Row 2: [ssk, k2, m1, k2, m1, k2, k2tog] twice.
Row 3: K 1 round.
Repeat rows 2-3.
Row 6: [k3, m1, k4, m1, k3] twice. (24 sts)
Row 7: K 1 round.
Row 8: k1, mb, k8, mb, k13.
Knit 3 rounds.
Row 12: [k2, k2tog] 6 times. (18 sts)
Row 13: K 1 round.
Row 14: [k1, k2tog] 6 times. (12 sts)
Row 15: K 1 round.
Row 16: [k2tog] 6 times. (6 sts)
Break off yarn and thread end though remaining sts. Pull tight to gather, then thread yarn end to wrong side.
Turn alien inside out and secure this yarn end. Attach safety eyes if you're using them. To make antennae, thread a length of yarn under a couple of sts on the top of the head (on the wrong side) and knot securely in the middle, then thread the yarn ends to the right side. Turn alien right side out. Adjust position of antennae if necessary, then knot yarn and trim to 1". Stuff body. Sew bottom side of body, adding a bit of stuffing to legs before closing the seam. You may need to make a couple small stitches around bobble arms to close any holes. Embroider a face if you like.
Knit Flat: 3 mm (US size 2.5) straight knitting needles
Cast on 22 sts. P 1 row.
Row 2: k2, m1, k2, k2tog, ssk, k2, m1, k2, m1, k2, k2tog, ssk, k2, m1, k2.
Row 3: P 1 row.
Repeat rows 2-3.
Row 6: k3, m1, k6, m1, k4, m1, k6, m1, k3. (26 sts)
Row 7: P 1 row.
Row 8: k8, mb, k8, mb, k8.
Work 3 rows in st st.
Row 12: k1, [k2, k2tog] 6 times, k1. (20 sts)
Row 13: P 1 row.
Row 14: k1, [k1, k2tog] 6 timesm k1. (14 sts)
Row 15: P 1 row..
Row 16: k1, [k2tog] 6 times, k1. (8 sts)
Break off yarn and thread end though remaining sts. Pull tight to gather. Sew back seam, then follow finishing directions given above.
k = knit
k2tog = knit 2 sts together
m1 = make one by picking up loop between stitch just worked and next stitch, and knit into the back of this loop
mb = make bobble: kfbf, turn, p3, turn, k3, turn p3, turn, k3tog.
kfbf = knit into front of next st, then knit into back of the st, then into front again. Makes 3 sts from 1.
p = purl
ssk = slip 1 st, then slip the next. Insert left needle into the front loops of the slipped sts and knit them together through the back loops
st or sts = stitch or stitches st st = stocking stitch