Sewing Fishnets from Yarn

I have not, but I think it would work... You would likely have to work with lace weight or thread and 000 or smaller needles, depending on the size of the doll. It might be easier to start with a simple shirt, just to test out the fabric...

I would look on ravelry for a fishnet pattern to learn the technique.

 

Have you thought of using a macrame pattern? Try googling that and you might find a pattern. I believe macrame grew out of the fisherman's art of tying knots to create fishing nets.

 

There are several traditional knitted-lace patterns that produce a fishnet look -- it will take some trial and error to figure out what size needles to use with the yarn you have, but generally speaking, lace is knitted on needles at least 3-4 sizes larger than normal for the yarn. (That keeps the pattern open and airy, but it also means that the knitted fabric blocks to much larger dimensions than usual.)

Purse stitch is the easiest lace pattern of all time, and at a big enough gauge it has a good fishnet effect:
Cast on an even number of stitches.
*YO, P2tog* repeat to end of row or round.
Every row or round is the same.

Horizontal Lace Stitch is also a pretty good fishnet lookalike. It should be knitted in rows, not rounds (because it is based on garter stitch).
Cast on a multiple of 2 stitches.
Row 1: *YO, k2tog in back of stitches* Repeat to end of row.
Row 2, 3, & 4: Knit.
Repeat Rows 1-4 for pattern.

 

I'm with @LisaMarie; macrame or knotting is the way to go! The knitting patterns are very awesome, but I think it will work up a lot quicker as a knotted piece, and you might have more control over it while you're making it, since you'll be able to constantly check it against your specific doll's leg.

 

I haven't tried it myself but if you can crochet, I have seen lace crochet using tiny hooks, the ones that are numbered instead of lettered for sizes. This video uses larger yarn/thread and hook but it should be easy to adjust it to a bjd size:

 

I have only made a hammock:
ZZZZ.... by spih_2, on Flickr

You could try to Google "net weaving" if you want to learn the technique.

 

That is so cool!