Out of various reasons, I selected the Futurama Planet Express logo. It is simple enough for a "quick" try, geeky enough to be put on a crate/box and multi-color. Aaand it is available as vector graphic / svg from here:

http://theinfosphere.org/Planet_Express

The svg differs from the logo from the planet express ship in the series (ship is black), but that is an easy change.

The svg was split to 3 parts, printed on DIN A3 250g paper at the copy shop and cut out:

1. big (white) and small (red) ring:

2. black rings:

3. text and rocket:

The inner parts of P, A, P, R were fixed in place by copper wire and glue:

...the cheapest spray paint available at the local hardware store:

...applied layer after layer on cardboard and wood (massive transport trolley thing):

- big white ring

- let it dry!

- small red ring

- let it dry!

- two black rings

- let it dry!

- rocket + text

Lessons learned:

- either use water-proof material (plastic foil) or first paint complete stencil to prevent it from bending due to moisture form paint

- add alignment points to all stacked stencils, else it gets hard to align them (d'oh!)

- normal thick copper wire (1...1.5mm²) works great as support structure

- add bigger border to stencil (easier masking)