Adonboard

A suitcase spends its life in baggage claim, on trains, in hotel lobbies and in the background of other people's photographs. Nobody was selling that space.
Adonboard is a marketplace for it. A traveller lists their case: its size, colour and shell, where it is going and how often they fly. They lay out sticker spots on a 3D model of the case, set an opening price for each, and publish.
Brands bid. Every bid must double the one before it, so nobody nudges a spot by a euro and a contested spot finds its price quickly. A traveller can also offer spots at a fixed price, for whoever claims them first.
When bidding closes the winners are charged, the traveller receives the logos, applies the stickers and photographs them on the real case. The brand approves that photo from their dashboard or by email, and approving releases the traveller's share. If the stickers never go on, the brand gets its money back automatically.
Stickers stay on for a term the traveller sets, from three months to two years. What a brand buys is physical presence in airports and stations, on a named kind of traveller, plus photographs it can use. A spot costs 30 to 95 euro, which is less than a single piece of commissioned travel content.
Listing is free. Adonboard takes 10% of a winning bid and nothing else. Payouts run through Stripe into the traveller's own bank account.