This detailed Victorian mansion exterior is supplied as a single 1:87 (HO) master STL, designed as a scenic centerpiece for HO layouts, dioramas, and display models. The late‑19th‑century composition is deliberately asymmetrical: a steep front gable anchors the principal façade while a secondary cross‑gable interrupts the roofline. Two projecting bay‑window assemblies (one single‑storey, one two‑storey) create vertical interest and deep shadowing, and a recessed porch with stout posts provides a convincing entry. Trim details — raised cornices, layered eaves, pronounced window surrounds, simplified balustrade and relaxed finials — have been thickened where necessary to survive both resin and filament printing. Included: one master STL locked to HO (1:87) scale. No pre‑scaled files are included; to print at a different scale uniformly rescale the HO master in your slicer or CAD tool (example: 1:87 -> 1:43 scale ≈ 2.023). Resin printers (SLA/LCD) will best capture cornice and reveal relief; use fine layers (25–50 μm). For FDM, orient the façade to reduce support contact, use a smaller nozzle if available, and plan supports under projecting bays and porch overhangs. The model prioritizes exterior architecture and scenic massing rather than interior furnishing; split the roof in your CAD environment if you need removable sections for painting or lighting. This piece makes an effective residential landmark on an HO main street or a detailed diorama focal point.