Two-person lap afghan
Like most of my patterns, this was inspired by the yarn available. In particular, I found a cubbyhole in a yarn shop with the same make and model of yarn in five colours, but three of them only had one skein each. It was the middle colour on the spectrum that had the most available, and the basic idea was born in my head---wavy stripes of four colours alternating with stripes of the background, middle colour. The final size is about four and a half feet long by six feet wide.
Yarn: 7 4oz skeins Blackberry Ridge bulky yarn, in five colours: 3 medium grey-brown (MC), 1 dark brown, 1 medium brown, 1 light grey-brown, and 1 off-white (CC).
Needles: US-15 29" circulars. Trying to do a piece of this size on straight needles is theoretically possible but not recommended.
The basic pattern is quite similar to "Welting fantastic" from Barbara Walker's Treasury of knitting patterns. However, I wanted something a bit lacier for the parts in between the "welted" stripes, so I threw in a few yarnovers and made a few other changes.
The pattern row
s1, k1, k1+1, * (yo, ssk) x3, s2sk, (k2tog, yo) x3, 1+k1+1, rpt from * except last time end with 1+k1, k2.
The increases work as follows: k1+1 means, knit a stitch as normal, then with the left needle pick up the stitch under the one you just knitted, and knit into that. (aka a "lifted knit left increase") 1+k1 is similar, but here the increase comes before the regular knit---first, use the right needle to pick up the stitch below the one you would otherwise be knitting into, and lift this onto the left needle and knit into it, then knit your regular stitch. (aka a "lifted knit right increase") Finally, 1+k1+1 does both, first picking up the lower stitch and knitting it, then knitting the regular stitch, then picking up the lower stitch again and knitting it.
The s2sk decrease is a double decrease: slip two stitches as if to k2tog, then slip one more as if to knit; then insert the left needle into these three stitches and k3tog. (This is identical to ssk except that the first slip takes two stitches instead of one.)
When starting a new colour (rows 10, 16, A, and E below), the first slip stitch should be replaced with a p1; this preserves the pretty chain selvedge and means you won't have to do any edging later.
The main pattern
Loosely CO a multiple of 16 stitches, plus 5. (I used 165 stitches; this definitely yields a two-person-wide blanket.)
Rows 1-9: s1, knit to end in CC.
Rows 10, 12, and 14: Work pat row in MC.
Rows 11, 13, and 15: s1, k1, purl to last two, k2 in MC.
Row 16: Work pat row in (possibly new) CC.
Repeat rows 1-16, ending on row 9, then bind off in CC.
The bridge pattern
As I approached the middle of the piece, I was able to estimate how much yarn I'd be left with, so I knew I could fit a few more rows of each contrasting colour and quite a few more of the main colour, forming a "bridge" between the two sides of the piece. After line 15 of the fourth repeat of the main pattern, switch to the following:
Rows A and C: Work pat row in MC.
Rows B and D: s1, k1, purl to last two, k2 in MC.
Row E: Work pat row in CC.
Row F: s1, knit to end in CC.
Repeat rows A-F, ending on row D; rejoin main pattern starting at row 10.
Don Blaheta / firstname.lastname@example.org