The Neighbourhood. Lots are 100 mm squares of lawn with a sidewalk along the front and the same joint on all four edges, so they click onto the side of any straight and onto the next lot. Four pegs stand on each lot; every building has the same four holes underneath, so any building sits on any lot and lifts off. The garage is open at the front - a car drives in. The roofs lift off too. A hole at the front corner takes the traffic light or the stop sign.
How it fits together. Every road end carries the same dovetail: a tab on the left, a socket on the right, so two ends meet whichever way round they're turned, and a set clicks onto any other set. Tiles are 3 mm PLA plates with the curb line and the lane markings raised on top in their own colours — the joints have a little clearance and hold on a hard floor or a rug. A straight is 100 mm; a junction is the same, so the town lays out on a grid and a loop always comes round. The roundabout is 200 mm across, the largest piece, printed flat on one bed. Nothing is glued; nothing has small parts.