Ho Scale Historical Ashlar Tunnel Portal System

/// QUICK SPECS ///

• Native Scale: HO (1:87) — Includes exact slicer percentages for O, S, N, and 28mm scaling below.
• Geometry: 100% Manifold, Watertight.
  The Deep-Solve Pipeline: Hours of custom historical research, manual optical reconstruction, and digital artifact restoration.
• Print Difficulty: Easy to Moderate (FDM prints the facades cleanly on their backs; Resin requires aggressive hollowing if printing the massive full-depth wedge).

Carved from the bedrock to tame unforgiving mountainous terrain, this heavy ashlar stone tunnel portal has borne the brunt of a century of rail operations. Chiseled blockwork, stained by decades of pounding diesel exhaust and relentless freeze-thaw cycles, stands as a testament to early railroad engineering. The brutalist, oversized keystones and heavy wing walls were designed to hold back mountainsides, shrugging off mudslides and ground tremors with unapologetic permanence.

The physical reality of this asset is defined by deep, rugged surface texture and structural heft. Look closely at the chipped edges of the stonework and the uneven mortar lines that refuse to lie perfectly flat—this portal is meant to be deeply embedded into a plaster mountain or carved foam embankment. Engineered as a modular system, the files offer both thin, space-saving facades and a massive full-depth wedge. This guarantees perfect clearances for your rolling stock, ensuring that even modern double-stack intermodal well cars can confidently blast into the darkness without scraping.

/// ALTERNATIVE HISTORICAL APPLICATIONS ///

• Appalachian Coal Route: Embedded into a steep, heavily forested plaster mountainside to anchor a grimy 1950s coal drag line.
• Modern Intermodal Corridor: Utilizing the double-stack clearance facade for a contemporary, high-speed rail line passing through a weathered, legacy stone cut.
• WWII Historical Wargaming (28mm): Anchoring a European tabletop board as a strategic, fortified rail chokepoint or a hidden mountain supply entrance.

/// FILES INCLUDED ///

• Modern_Double_Stack_Clearance_Thin_Facade.stl: A streamlined facade engineered with extended vertical clearance to accommodate modern intermodal well cars.
• Standard_Era_Clearance_Thin_Facade.stl: A historically proportioned facade perfect for steam and early transition-era rolling stock.
• Standard_Era_Full_Depth_Source_Wedge.stl: The massive, full-depth structural wedge for building complete, heavy-duty tunnel interiors.

Restored & Remixed by Entropy Archives.

/// SCALING GUIDE ///
This historical artifact is natively scaled to HO (1:87) to match standard model railroad infrastructure. However, because this is an ultra-high-resolution photogrammetry mesh, the extreme surface detail allows for massive upscaling without looking blocky or losing texture.

Use these exact percentages in your slicer to convert to other common scales:

• O Scale (1:48): Scale up to 181%
• S Scale (1:64): Scale up to 136%
• 28mm Historical / 32mm Diorama (1:56): Scale up to 155%
• N Scale (1:160): Scale down to 54% (Resin printing highly recommended at this size)

/// RECOMMENDED PRINT SETTINGS ///

FDM: Print the thin facades flat on their backs directly on the build plate to completely eliminate the need for supports. For the full-depth wedge, print upright with standard tree supports for the archway roof. A layer height of 0.12mm to 0.16mm is highly recommended to capture the rough stone texture cleanly.
Resin: Print the facades flat on the plate or at a slight 15-degree backward tilt. If printing the full-depth wedge, aggressive hollowing and heavy drainage holes are absolutely mandatory to prevent massive suction-cup failure and wasted resin.

Restored & Remixed by Entropy Archives.