I was creating a terrarium for my Ruby eyed tree frogs a few weeks ago and discovered a great way to make a large "in-ground" pond - Disposable Paint trays. They can be found in all sizes, and have that nice slope so one end is deep and the other comes right to the surface. (plus they are only $1.99) I have 2 black ones in that tank that are awesome, and are plenty large to put a pump into. Just put moss or large stones around the edge and it looks very natural.
Just thought Id let you all know
I can post a pic if anyone is interested