Help with indoor ponds for fairy tale scenes

What do people use to put indoor ponds in fairy tale scenes not a plexiglass mirror but actual water. Please help.

Plastic pond liner from Home Depot, or some rocks holding a small section of above ground pool liner or just some heavy plastic. Then disguise the edges.

Ryant35 is right on, any type of form will work as long as it is heavy enough so it doesn't move when the pond is filled with water. You could use plants to disguise the edge. Also one piece of advice, keep electrical cords and such at a safe level above the floor. Accidents do happen. I worked on a car commercial in a studio with a pond made that way. The dam broke and water was everywhere, we were running for our lives because electric cords were all over the floor.