Sewing pattern recommendations for diaper covers?

I have a bunch of old shrunken sweaters that I’d love to turn into diaper covers. I’m already turning the nicer cashmere sweaters into baby pants and hats, but thought the thicker shrunken ones would be good diaper covers.

I have a couple of nice sewing machines, sergers and Kam snap fasteners (I run a small textiles studio). So I have the equipment and skill, but I’m really unsure about sizing, this is my first baby and sizing clothing in general is not my strength, so a printed pattern would be super helpful.

Thank you!