An actor can be buffered, the same as any other send channel. By default, all actors are unbuffered: they suspend the caller on send() until the message has been received. To create a buffered actor you need to pass the capacity parameter to the builder:

fun main(args: Array<String>) {
    val bufferedPrinter = actor<String>(capacity = 10) {
       for (msg in channel) {
           println(msg)
       }
    }

    bufferedPrinter.send("hello")
    bufferedPrinter.send("world")

    bufferedPrinter.close()
}