I've started work on Plurum's tower design screen! This is where you put together the towers you can use in-game out of up to three pieces of hardware and up to three addons. In future you'll even be able to design the projectiles these hardwares fire!
Save the configuration under a name (a favourite of mine is "The Pastemaker") and you'll have it available in-game for building. Remember, the bigger, the pricier! You're paying by the bullet.