This decoration for knitted projects looks like Latvian Knitting, but is really just crocheted slip stitches made into a knitted foundation. It's really easy to do and is a very effective way to add design interest to your knitting.
This pattern is for knit slippers, but I can totally see using a wool sweater and cutting and serging slippers from it! Home Slippers - DIY. this is knitting, but I bet I could use this to crochet some