For the Mandala flower, here is a step-by-step photo gallery. To do this you start at step 1 with 7 strings attached and 6 with Einhängeschlingen on 7 folded thread. Other threads are then inserted by most of us with an ordinary shoelace knot.
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