If you go goblin you can get a BoP schematic to make a walking bomb pet.
If you go gnome you can get a BoP schematic to make a small robot that is continually spewing smoke.
The only way to get these schematics is to renew your membership card. You need to speak to one of the trainers to renew your membership card. Doing so costs a gold or more. It’s been so long since I’ve renewed my membership that I don’t remember. Each time you renew your membership you will be mailed a gift within about 24 hours. This may be something like a mithril casing or it might be the pet schematic. It’s completely random. All I can tell you is that the pet a rare “drop.†You may get lucky and get it the first time. But I know of several engineers that have renewed over 100 times without every getting the pet.
Best of luck.