Minecraft 1.8: execute multiple commands with only one command block
This is a Lua (5.2) script which takes as input a list of commands and gives you a single command back that you can execute in a command block and all command from your list will be executed in order. In case the command is too long or the generated FallingSand tower is too high, it is split up into multiple commands.
For instructions on how to use it, look inside the file itself.