All weapons in our game fall into predetermined size criteria that determine what type of weapon it is. If this thing somehow fit these criteria and is determined to be safe for use in combat, then yes. If you have something that is outside the weapon criteria, or is determined to be unsafe in any way, you will not be able to use it.
Before you go and build anything that you are unsure about I suggest looking at the Weapons & Armor section on the navigation bar to your left, which is where you can find the specs for weapons.
Okay, THIS makes me curious. Is there a siege size weapon catagory, and if not... could we make one?
Like a giant pillow-launching catapult that delivers three bash attacks if it hits a door!