My suggestion would be to consider doing a set for H.E.R. as well. The base figure is free over at Sixus1, and any of the girls can always use more casual clothes. So can the male figures, for that matter. :) As far as texture suggestions, the only sandals I've seen like these were a pair my mom wore when I was little. The toe strap was leather, and the sole of the sandal was polished wood, with (I think) a thin rubber tread glued on the underside where it would touch the ground. The leather strap would have had a buckle on it, but it would probably look ok as just a single plain leather strap as well.