The 2-month long process of designing a trailer, finding a good metal fabricator and having a wood box and counter built, finally came to an end. My carpenter friend did an amazing job with the box and table. It's all plywood, so the weight of the empty trailer is still under 20kg (+ 20kg icebox inside).
Had seen a spot the week before on the bike path near the 85F building that looked good. Lots of folks playing with their kids at a wading pool and no coffee or tea shops within 500m. It's a 45 min. ride from my house, so I got a good workout riding there and back. The trailer is about 40kg empty + a 25kg bag of ice + 25kg of coffee and Thai milk tea = 90kg. Rolls great on the flats, but at the slightest of inclines it feels like all your tires have simultaneously gone flat.
Lots of folks came over to enjoy some ice coffee and take photos with their phones. All in all, a great first day with a much lighter load for the ride home.