In lieu of the acrylic dough doubler buckets(http://www.kingarthurflour.com/shop/detail.jsp?id=5060 [1]), what do y'all use for rising your dough that you can really see through and verify doubling? I can't handle buying a bucket for $15.. that doesn't make sense to me.  I've always just used a set of opaque plastic bowls, but now that I do sourdough doughs, it is becoming more important that I wait for doubling.

 -Loafer