You will have to bring three items needed for a proper heist. Note you can create either weapons or equip disguises on Maxwell.

Set 1: Disguise on Maxwell, Gun, Axe
Set 2: Mask on Maxwell, Rubber Glove on Maxwell, Weapon
Set 3: Moustache on Maxwell, Bomb, Dynamite

Scribblenauts Remix 1-8 Cheats Hints gallery:
1-8-1-a: Maxwell is planning a heist. His gang needs three items.
1-8-1-b: Give Maxwell a disguise.
1-8-1-c: Maxwell could use tools to break into a safe.