A 10-minute challenge

[steve.ledger]

Hi Javier,

This is almost a 6 year old thread in which the original poster neither revealed the 'trick' (as promised) or has visited the forums in three years.

Perhaps your image would be better suited to the December 2008 Stop and Post?

[jvila]

Sledger, I didn't realize about that detail, you're right, my apologies.
Best regards