Rails with randomised planks I'm trying to generate lots of rails using "animation nodes" and after "googling" I have something like this on the screen. But I have one problem, I don't know how to use more than one object for this crosswise planks.

Right now I have connected "Object Instancer" , how can I add multiple object instancer with random placing of this planks? 

In other words I'm looking for a methods to duplicate randomly 3 elements along the curve.

Best!
Instead of instancing a single object, create a number of empty objects using the Object Instancer Node with the Copy From Source option disabled. Then get a list of all objects that has the meshes you want, generate a random list from them using the Random List Node and copy the data from the objects in this list to the empty objects you created using the Copy Object Data Node.