Blueprints can be purchased from merchants across the battlefield like Siegemasters and other NPCs, found as rewards for completing jumping puzzles in the Mists or as drops from other players, guards and dolyaks. 
|Alpha Siege Golem||1||100||100|
While Soulbound, Blueprints may currently be given to other players by placing the bundle in your hands while in a Borderland (double-click the desired Blueprint) and dropping the bundle (e.g. by using the weapon swap key). This will create an object on the ground that can be picked up by anyone as the originally used Blueprint. Just make sure there are no enemies nearby!
 Superior Siege weapons
Superior versions of each siege weapon blueprint can be created in the mystic forge (named Omega in case of the golem). These do more damage, but are considerably pricier.
 Guild Siege Equipment
A "guild" version of the catapult and the Alpha Siege Golem exists. These have to be produced by the guild, using influence. Unlike normal siege weapons, they are not activated via blueprints, but directly from the guild upgrade tab. The main advantage is a lower supply requirement of the resulting build site.
In addition, special guild blueprints of trebuchets, catapults, ballista, and arrow carts can be purchased from the Guild Commendation Trader. These siege weapons display your guild emblem and are account bound.
Blueprints can be placed on the ground anywhere in WvW battleground as a build site.
Any player can do so by using a blueprint from their inventory, which changes their skill bar with options to:
- Put back away
If dropped, a bag of loot containing the blueprint appears on the floor and anyone can pick it up.
Build site created by placing a blueprint.
- Built Siege gets removed if it is not used in a certain amount of time.
- ^ http://www.arena.net/blog/mike-ferguson-on-guild-wars-2-world-vs-world
- ^ http://www.arena.net/blog/mike-ferguson-takes-your-wvw-questions-here-and-on-reddit
- ^ Mike Ferguson, on the official forums,It is indeed intended (and bizarre). We would actually prefer to just make the blueprints tradeable, but there are a couple of funky code interactions that happen to make that impossible for us currently. It’s something we’d like to address at some point, but it’s not very high on the priority list currently.