The first part of the zombie shield is a tool that you can find in the room nearest to the second dog in any corner.
The second part is in any corner of the gondola´s path where you can find the mystery box.
The third part is a car door that you can find in any corner of the catacombs.
You can use the zombie shield as a bodyguard, as bait, or to hit zombies. When it breaks you can get it again from the table.
Parts of the Acidgat Kit:
The first part can be in three places.
The second part is in any corner of the Warden´s Office.
The third part is in the hallways close to the third dog.
The Acidgat Kit is used to upgrade the Bloondergat into Acidgat. You can build it on any table in Mob of the Dead.
You can see how to make it in this video: Acidgat and zombie shield
