I have made a couple of "water features" for my Dungeon Crawl Project for which I have been using floor tiles from DMB Games.
I bought a rope bridge from DMB Games at Salute and have now made a Green Pool Of Doom over which it will span:
I also made a water (or oil) filled pit trap. Here I lay out a normal 2 square wide passageway and then replace one of the 2x2 tiles with this piece when the trap opens:
Both water features were made from plasticard. The plasticard was painted the desired colour, in this case Snot Green and Black. They were then covered with Liquitex Gloss Heavy Gel Medium. For the Green Pool I used the Gel straight out of the pot. For the Pit Trap I mixed in two drops of black ink and two of brown. (It works great mixing acrylic inks or paints into the Gel).