This is a description of the building of Kent's indoor pond which has been built using shuttering, and then pouring the concrete.

First we dug about 1.7+meter deep. After a layer of sand we poured 2" of concrete over to get a working ground.

As seen in this photo the 3" pipes are assembled (a bit tilted towards the waste chamber) and held using bricks and cement. Then the 8mm iron bars as the "skeleton" of the pond's base and walls. The 8mm iron bars were laid out in a criss-cross pattern forming a mesh of 20cm x 20cm.
A bit more than 3" layer of concrete is then poured in, just to cover the 3" pipes.

After a day, we fitted two 4" bottom drain pipes, two 1" return pipes, one 2" overflow pipe, one 1/2" air pipe and two 1.5" waterfall return pipes are fitted in. As seen here the casting is prepared using 6mm plexiwood and 10cm x 8cm lumber, and also lots of nails.

In the photo on the left you can see that the shuttering is all complete and the concrete has been poured in. After a week when the cast had set then the wood was removed as can be seen on the right.