Bobble Crochet Pillowcase Edge

I love bobble edge trim and wanted to try and replicate a bobble edge using crochet. I'm sure there must be another way of making a crochet bobble but this is the only way I know.

Foundation Row  Edge the pillowcase using blanket stitch, 1cm down from the edge and the stitches 1cm apart

Join the wool in to a blanket stitch using sl st

Make bobble - Ch4, 3tr (leaving the last loop from each tr on the hook), pull wool through all 4sts, ch4, sl st in to htr.

Row 1  - 3dc in to each blanket stitch, join the row end with sl st

Row 2 - 4ch, skip 2dc, htr in next dc, * 2ch, skip 2dc, htr in next dc. Repeat from * to end, sl st in ch2 of beg 4ch.

Row 3 - Ch4, 3tr (leaving the last hoop of each tr on the hook), pull wool through all 4sts, ch4, sl st into beg of 4ch, * 2 sl st across 2ch, sl st in to htr, 2 sl st across 2ch, sl st in to htr and make bobble. Repeat from * to end. Fasten off with sl st.