Video Tutorial

Start making a chain multiple of 6 stitches (see the video to know how to make the measurements)
Row 1: Chain 1, 1 single crochet in all the stitches
Row 2: Chain 3, 1 double crochet around
Row 3: Chain 1, skip 1 stitch, chain 1, 1 single crochet, *chain 1, skip 2 stitches, 1 double crochet, chain 3, 1 double crochet in the same space, chain 1 skip 2 stitches, 1 single crochet*. repeat from * to * to the end of the row
Row 4: Chain 3, *1 puff stitch (3 loops) , chain 1, 1 puff stitch, chain 1, 1 puff stitch (in the chain 3 space of the previous row), chain 1*. Repeat from * to * to the end of the row. 1 double crochet on the last stitch
Row 5: Chain 3, *1 double crochet on the chain 1 space, chain 1, 1 half double crochet on the chain 1 space (between the puff stitches of the group), chain 1, 1 half double crochet on the chain 1 space (between the puff stitches of the group), chain 1*. Repeat from * to * to the end of the row
Row 6: Chain 1, 1 single crochet around
Row 7: Chain 3, 1 double crochet around
Row 8: Chain 3, skip 3 stitches *1 double crochet, 1 double crochet on the previous stitch (1 crossed double crochet), skip 1 stitch*. Repeat from * to * to the end of the row. Finish with 1 double crochet
Row 9: Chain 3, 1 double crochet around
Row 10: Chain 3, skip 3 stitches *1 double crochet, 1 double crochet on the previous stitch (1 crossed double crochet), skip 1 stitch*. Repeat from * to * to the end of the row. Finish with 1 double crochet
Row 11: Chain 1, 1 single crochet in all the stitches
Row 12: Chain 3, 1 double crochet around
Row 13: Chain 1, skip 1 stitch, chain 1, 1 single crochet, *chain 1, skip 2 stitches, 1 double crochet, chain 3, 1 double crochet in the same space, chain 1 skip 2 stitches, 1 single crochet*. repeat from * to * to the end of the row
Row 14: Chain 3, *1 puff stitch (3 loops) , chain 1, 1 puff stitch, chain 1, 1 puff stitch (in the chain 3 space of the previous row), chain 1*. Repeat from * to * to the end of the row. 1 double crochet on the last stitch

Turn and repeat the same from the foundation chain to the other side making a symetric piece

Make 2 pieces. Sew 2 sides on the back part, cross the vest in the front part, and sew the other 2 sides also on the back part. Sew the two parts of the back part together