The model shown has a sole length of 3 3/4 inches, approx. for baby size 0-4mos. Use 1.75mm hook to get a bigger size.
You can use size 8 or size 10 cotton thread, with 1.5mm or 1.75mm crochet hook. For the model shown, size 8 thread and 1.5mm hook was used.
For the ties, you can use 1/4” satin ribbon, or crochet ties with a ball or flower embellishment. Instruction for ties and embellishment is included in the pattern.