When the recipient opens their post box, the pop-up will stand out and grab their attention. Because it’s unique and playful, they will probably not through it away and also show it to others.
Print your advertising on the paper, and have pop up boxes made from it using folding and rubber bands. Then distribute it to post boxes in your business’ local area. It should be packed flat for distribution and slid into the post box, where it will pop up (partially or fully depending on the size of the post box), and wait to be discovered.
Most flyers go directly from the post box to the trash can.
Use the flyer to do just one thing: get their attention to participate in a game where they can win a prize. Similar to only selling the click in an online ad, you should only sell the first action: they should join the game. The game (treasure hunt, riddle, online and offline) then leads them to you through a funnel.