Hi there everyone,
Long time lurker, first time poster so please be gentle 
I am looking for ways to join together several swatches with visible seams, a bit like this:
But knitting instead of crocheting - do you have any suggestions as to how this could be achieved?
Thank you in advance!
Welcome to KH and to posting on the forum!
You could pick up sts along an edge of one square, knit or purl a row and then join to picked up sts on the second square. You could do this directly without knitting or purling between the edges.
Three-needle bind off with the seam to the outside would work between picked up sts too.
This join uses a crochet hook and a slip stitch but it’s so neat and pretty that you might consider it.
Oooooh this is excellent, thank you!