Found no such stuff on YouTube, therefore I claim this as the first. PM me if it isn't.

The perfect solution to squeeze several missiles into your slimeblock war machine.This thing stores up to 8 missiles in a long chain, perfect for breaking through protective barriers.

This is pretty compact(32x4x5)for 3 missiles.

Note: The reason that I did 3 missiles not 8 is that 32 is the max length stored in the structure block, and there are other stuff in that world as well. Also I was lazy :3

PS: Hope you can figure it out because I'm not gonna tell you how to operate it.