Had I been subjected to the same nightmarish labyrinth featured in the Portal games, I would have preferred a more substantial reward than cake at the end anyway. Like these adorable light and sound keychains.
The miniature $25 turret includes an ominous glowing red LED and sound effects from both the original Portal game and the sequel, the perfect way to remember what was trying to kill you during your escape. While the $20 Wheatley avoids having to pay royalties to Stephen Merchant by just simply lighting up with a blue LED reminiscent of his single eye.
It seems to me like the portal gun itself would have been the obvious accessory to miniaturize, but these options are just as perfect if you've got a Portal fan on your Christmas shopping list. [ThinkGeek]