I bought similar waterproof fabric from Ikea last weekend to make another smock for Adam. The surface of the fabric is matte, not shiny like Mia's smock. It turns out that is easier to sew with and it has better drape too. Recommended! Ikea has it in a few other prints..
I made it similar to Mia's, but cut a bit straight (and not so girly) and wider. The sewing is a bit wonky as you can see. Just a quick after-dinner sewing and completed in just about an hour.
(they already do, come to think of it)