You can either do a circular swatch or a 'fake' circular swatch where you knit across on a dpn and then let the yarn drape across the back and knit across the row again after sliding it to the other end. This way all the stitches are knit.
For Barbie, though, I'd probably just start knitting and maybe do a gauge measure then.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry