I would like to create basin for a water feature. It would look really cool if it can have a fake rock finish.

How would I go about creating it? What material would be recommended, I have seen a couple for sale and it seems to be made of fibre glass. I can buy it, but I would prefer to make it myself.

  • It's actually trickier than you'd think to make a mold of an existing rock; the issue is that you have to plan where you're going to put the seams, so that any knobby bits sticking out aren't going to catch the mold when you try to remove it.
    – Joe
    Feb 8, 2011 at 1:02

3 Answers 3


There are several types of silicone molds that can be filled with regular concrete. There is a limited selection at the box stores, but you can find lots of different designs online. These are nice because you can use cheap bagged concrete mix, add colored dye if you want or even put in real stones and embed with the concrete. Most of these molds are fairly small, 3 ft by 3ft and make 2 to 4 stones each.


If I had to make something, I'd probably go with strofoam, carve it to shape, than coat it in bondo or other automotive body filler.

If you need extra durability, you could go with an epoxy & fiberglass layer over the syrofoam, before you applied the auto filler:

  • first, make sure you don't mind ruining whatever you're wearing
  • cover your work surface, as epoxy cleanup sucks.
  • cut strips of fiberglass
  • Mix a batch of slow cure epoxy (not the 5 minute kind)
  • paint the epoxy on the surface
  • press the fiberglass into the epoxy (wear disposable gloves)
  • paint more epoxy over the top of the fiberglass
  • repeat with the fiberglass going a different direction.
  • end with a layer of epoxy
  • let cure overnight, or however long the epoxy instructions say.
  • cut the item free from whatever surface you left it on.

I've never painted something with a rock finish, though. I've seen it done on home decorating shows, generally using sponges or crumpled paper (I admit it ... I used to watch Changing Rooms when it was on ... I wasn't so much a fan of what the Americans did with it ... well, Vern's designs were usually good, the rest all basically had a set style, and kept doing the same thing over and over again)


Let's blend Joe and Holmes' answers.

  1. Take a hard foam (like the weird green kind used for some packaging/fake flower beds) but i'm not sure the best place to get this. Use this to make the rock shape you are looking for with files and knives.

  2. Cover the upward/forward facing surface with a silicone epoxy and let sit to dry overnight.

  3. Fill a container with sand, large and deep enough to hold the epoxy form you made. Obviously the sand will help the form keep it's shape.

  4. Fill form with concrete or whatever medium you choose and let dry.

  5. Place beautiful new rock in rock garden and contemplate life!

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