For both professions, only two items are Bop:
Gnomish: Death Ray and Battle Chicken
Goblin: Dragon Gun and Bomb Dispenser
All other items can be traded. In other words, no, you cannot get a Death Ray as a Goblin engineer. But if you had a Goblin engineer as a friend, he could make and trade you a Goblin Rocket Helm. Or you could make a Gnomish Harm Prevention Belt and trade it to him.