I am doing a wedding cake for my sister and she wants a waterfall. The design is a 4-tier cake and I would like to make the waterfall go from the top tier to the bottom tier, which of course has a huge gap with nothing to hold the waterfall up. So, I am thinking using fondant is out of the question. The cake topper is dolphins made from fondant. So, my thought is to use card board covered with aluminum foil and then pour jello over it and refrigerate it until the wedding or either use piping gel over the foil.
My question is has anyone done something like this before or do any of you have a better idea than this? A drawing of my cake design is attached. HELP PLEASE!

What about doing one out of gumpaste that way it doesn't have to be completely flat ... dry it completely and them put your buttercream or just lustre dust it - it's early!

personally I have never done this but I have seen a few cakes on here that used the flower drying things to have a waterfall going from one cake to another.

Here's what I know from being crafty and having made a tabletop fountain.

I'm not sure if the uppermost cake with the dolphins is held up by posts are pillars. Is it sitting on top of the second layer?

You will need two receptacles, one for the water to pour out of and some type of receptable n the second layer to receive the water. You will also need a small pump which you can get from Michaels. They sometimes have brown tubes to carry the water, but a fish supply store would have clear tubing if the craft store doesn't. I suggest clear a acrylic (ie plexiglass) to act as the "ramp" for the water flow. It can be cut with a saw. You could make the edges wavy like water.

So I'm thinking of a small pottery urn glazed in a beautiful color or it could be a clear glass container. Turned on its side with water pouring out, it slides down the plexiglass(protecting your cake/icing) into the receiving receptacle (also glass??). The pump would return the water to the top layer through the tubes maybe hidden along your support pillar.

The fountains have a light in them for if it's a night wedding. Obviously, this waterfall wouldn't. I also have found that placing the fountain on a clear separator plate helps the water splashes stay off your icing.

I am crafty so I always love having an idea and constructing a solution.

This would be so very cool if you can make it happen!

PS. Once for a soccer banner for a team called the waterfalls, I simply used clear plastic fabric and put accessories between it fo represent the waterfall. You could do this and add piping gel, glitter etc. I"m thinking you could even carve out the edges of the cakes first to resemble the slope of a waterfall.

Here is an example of using a pump. I would definitely not set it up like this though. But it is a working example.

What about making a sugar waterfall using isomalt so the humidity won't be a problem.
You can take aluminum foil to make your shape, then lay it down and pour in hot isomalt mixture that you have colored blue. When it cools, it will be like lollipop consistency. You can make a couple of "shingles" of the water, when done, you can melt them together with a flame of sorts or use royal as the "white" of the waterfall, hiding the fact that you are gluing them together. I have made it before for a "pond" and used regular sugar (like making hard candy). Now that I know about isomalt, that sounds like the way to go.
I'm sure there are many links to candy making instructions. And I am sure there are a bunch of people out there who know better than I do about the sugar procedures.

good luck, hope you have pics when you are done!!

I see many picture on here of blankets being made with icing on top of plastic wrap. They flow just like fabric. Could you do something in that fashion?