Using up leftover wool.
Starting with 5.5mm needles, will see how it goes.

Regarding the P1 w/slip:
When picking up the ‘slipped stitch’ to put on the Left needle, you are pulling it out of it’s previous stitch - picking it up by the bar between stitches and turning it into a YO in the process.

(If you want the starting & ending colour to be in the background for the mesh part, you will need to reverse the MC & CC for the brioche rounds.)

The draw string is extra long, because I decided to use up all the remaining CC.