This one started small: a guide template for laying flex track. Along the way it grew into a software-defined geometry planner for N-scale flex track, with printed roadbed, piers and viaducts built up around that original idea.
The system came together through a vibe-coded viewer app that displays the whole layout in 3D and generates complete print plates ready to send straight to a Bambulab printer. The same app doubles as an assembly guide with exploded views, and it offers Explore, Assembly and Print plates modes for examining the loop, pulling roadbed parts apart and zooming into joints. Part codes and joint tags keep the plates organized, and one build plate even carries a SkyTrain station label.
Some details stand out. Variable curvature radius works quite well with no discontinuous curvature, and grade parameterization works too, with test prints of piers and viaducts already done. The printed track beds carry nickel silver or steel rails with plastic ties, and a double-track crossover climbs onto a curved elevated bed supported by printed piers. Flex track snaps onto compliant retaining walls, and glue will hold those joints down as well.
There are trade-offs and open ends, as expected at this stage. Printing the piers and viaducts turned out tricky, so banked curves are switched off for now. The sunken retainer was removed so the sleepers sit the way they would on cork, and ballasting stays possible later. The elevated passenger station, modeled with GPT 6 Astra, is judged not bad and will be printed now, then redesigned if needed. Printing is about 30% done, and a layout editor that turns pen-and-paper sketches into track curves via computer vision is the next step, with a demo planned for the next update.