Making Hollow rock structures

[fish4all]

I have been thinking about this for a little while and have only come up with 2 ways.

#1: Use clay to make the rock/structure and then hollow it out before baking or curing the clay

#2: Use some sort of mesh, maybe my plastic mesh idea and add sand to Tite Bond III to paint over the mesh to form rocks and caves.

Anyone have any other suggestions?

I ask because I want to make a larger terrarium, eventually, but I would like to move things around and not have such a permanent look to my enclosures. Having a series of different sized rocks and slabs would allow me to stack them and arrange them differently when I want to.

[UncleChester]

Cement or grout work well for fake rocks, and should go over wire or plastic mesh form with no problems provided the holes are large enough for it to flow through.

[deranged chipmunk]

Cement or grout work well for fake rocks, and should go over wire or plastic mesh form with no problems provided the holes are large enough for it to flow through.

yup, been there. grout is awesome to make "fake rocks"
why not make a negative mold from plaster, then you'll have the rock form that you can fill with whatever you like to mass produce rocks. say you have 7 rocks you like. cover them with plaster to make the negative mold. then you have 7 forms to choose from. pour grout in and smear it around, voila...hollow rock

[fish4all]

Mass production is easy, my parents have many ceramic molds if I want to just make a bunch for whatever. I want to customize them for my tank while taking into account the plants I want to use and the size of the structure. I will have to see if I can find anything that has survived my kids and everything else.

I have never worked with grout so I will have to look into it.

[deranged chipmunk]

I keep forgetting you have experience with ceramics. Duh, lol

[exasperatus2002]

Anyone have pics?