Textures
Idenden. A water based pre mixed texture that doesn't crack and flexes when dry. It can be coloured with stainers and it's also fire resistant. It's not cheap though. Mix it with granular materials like fine foam or crumb rubber chips, or even sawdust, and if you want a lighter version to use on cloths, you can mix in very fine glass beads.
Artex. A powdered texture that is mixed with water. You can then add PVA which will make it more flexible and help prevent the texture flaking off. Artex is not suitable for floor areas as it's too soft and it's not good on scenery that is likely to flex like vacuum mouldings. It is cheap though and you can add idenden to the mix to improve it's performance.
Crystal Gel. A waterbased gel that dries clear, crystal gel is lighter than Idenden and can be used on scenic cloths. Because it dries clear it can be used for things like stained glass windows. It also makes a good binder for foam crumb and rubber chips.
Vermiculite. An inherently fireproof lightweight particle that can be bound by Idenden or other binders. It's not robust enough for floors.
Foam Crumb. Small particles of foam that can be mixed in with Idenden or other binders. The resulting mixtures are OK on a floor especially in lighter traffic areas.
Rubber chips. Another material that can be bound together to foam textures. Rubber crumb is heavy and solid. Good for floors.