WiFi Mesh Recommendations for a Small Museum

pikester writes: I have a friend who is running a museum that is looking to make it more interactive for the visitors. To make this happen, the museum is going to need to have good WiFi connectivity throughout the premises. The good news is that the museum is pretty small. The bad news is that it is located in an old horse barn with many metal walls. I'm hoping to put in a mesh network for him, but most solutions I've seen are pretty bulky. I'm looking for recommendations for a solution that is easily mountable in the building.