I made these last year, but they still fit, yay.
For the skirt I bought some orange satin, and some spider web black sheer material and layered them together. I did a simple elastic band. Then I just added purple polka dot ribbon to the bottom edge.
For the shirt I bought a plain black t-shirt and cut out the orange satin and sheer black web material into an octagon. Then I just lined the outside edge with the polka dot material.