After completing October Frost in the Ravellenic games, I was all fired up to knit cables. It was such a relief to know that I could do it again!
Designing with cables is fun, but it can be tricky. You can't just stick the cable in without making allowances for how much it will pull in; cables suck up a lot of horizontal real estate. I saw once a woman wearing a beautiful summer top that used cables in a very ingenious fashion, forming a tighter fabric just below the bust. She said it was from the spring/summer Sandra magazine that year ... unfortunately, I can't remember what show it was that I saw her at, so I can't remember what year it was, but it sure was a good use of cables in the design.
So. Suppose you have a stitch guide that has a really pretty cable in it -- or several (if you're like me). How do you put the cables in without having the thing just pull in and hug you tight? You might make a bigger size, but that's an iffy way to design. I learned (from somewhere a long time ago, can't remember where) that for every stitch crossed in a cable, add a stitch in your knitting: a three-over-three cable would then have three stitches added to make up for the three stitches crossed over.
If you design a pair of gloves that have three two-over-two stitch cables up the back, add 6 stitches -- 3 * 2 = 6. If you're designing a sweater that is stockinette stitch on the bottom, but you want an interesting cably thing at the top, count the number of stitches crossed over on the row with the most cable crossings, and add the stitches to keep the same width in your knitting and to prevent puckering (unless you want that).
Cabling is a lot of fun, and designing with cables is even funner :) I was in the middle of designing a great cabled sweater for the knitting cruise when I had my stroke; I still have my notes somewhere. I lost hope when I found my cabling ability was compromised, but now maybe I'll pull it out and look at it again. The Isaac Evans knitting cruise goes out this week -- I sure miss doing that! I'll go with you knitters in my heart :)