In the era of food trucks, pop-up shops and temporary restaurants, when even underground dance parties are thrown in the bays of parked U-Haul trucks, it’s surprising that more of the art world isn’t getting on board with this wonderfully lo-fi business model that optimizes exposure through social media and the Internet and requires minimal entry costs. Enter Show and Tell, an ambitious foray into the world of the DIY mobile gallery organized by Sierra Stinson, a Seattle-based artist and part-time gallerist, and Victoria Yee Howe, a New York-based conceptual artist and former pastry chef.