How to Make a Diorama with a PLA / FDM 3D Printer

FDM (fused deposition modelling) printers — the type that prints in plastic filament (PLA, PETG, ABS) — have different strengths to resin printers, and in many diorama applications they are actually the better choice. Larger build volume, faster prints, lower cost per gram, and structural rigidity make FDM ideal for diorama backdrops, architectural elements, and base structures.

FDM vs Resin: Which to Use When

• Use FDM for: large base structures, building facades over 10cm, floors and walls, support structures, anything that will be covered with texture materials
• Use resin for: fine detail elements, figures, small props, intricate decorative elements under 10cm
• Use both together: print the structure in FDM, add detail parts in resin, add organic terrain with Green Stuff and Vallejo texture products

Recommended FDM Printers for Diorama Work

• Bambu Lab A1 Mini / P1S — fast, reliable, beginner-friendly with auto-calibration. Current benchmark for ease of use
• Prusa MK4S — higher cost but exceptional reliability and print quality. Strong community support
• Creality Ender 3 V3 — budget option, capable results with more calibration effort
• Bambu Lab X1C — high-end option with multi-material capability for colour printing

Filament for Diorama Work

• PLA: the default choice. Easy to print, takes primer and paint well, rigid. Best for most diorama applications
• PETG: slightly more flexible, better for parts that need slight give. More difficult to sand smoothly than PLA
• Flexible TPU: for rubber-like terrain elements (grass tufts, tentacles, soft organic terrain). Requires specific slicer settings
• Wood-fill PLA: contains real wood particles — can be sanded, stained, and looks naturally wood-like. Excellent for wooden terrain elements (crates, furniture, floors)

Slicer Settings for Diorama Terrain

In PrusaSlicer, Bambu Studio, or Cura:

• Layer height: 0.2mm is standard. For parts that will be covered with texture products, 0.3mm is fine and prints faster
• Infill: 15–20% gyroid or honeycomb for solid structural parts. For decorative terrain tiles that will be mounted on a solid base, 10% is sufficient
• Perimeters/walls: 3 perimeters (1.2mm total wall thickness) for most terrain. 4+ for pieces that will be handled or drilled into
• Supports: minimise overhangs in terrain design to reduce supports. Organic terrain designs can usually be oriented to print without supports

Post-Processing: Eliminating Layer Lines

Layer lines are the primary aesthetic limitation of FDM prints compared to resin. For diorama terrain this matters less — terrain texture often masks layer lines. But for smooth surfaces (walls, floors, architectural elements):

• Sanding: wet sand progressively from 120 → 220 → 400 grit. Works well on PLA. Time-consuming but gives the cleanest result
• XTC-3D epoxy coating: brush-on two-part epoxy that self-levels over layer lines. One coat, 5–10 minutes application, 4 hours cure. Excellent for large flat surfaces
• Filler primer: rattle-can filler primer in multiple coats (with sanding between) fills minor layer lines. Efficient for small parts
• Vallejo texture gel: for terrain surfaces that will be covered in texture anyway, simply apply Vallejo Dark Earth or similar texture gel over the print — the texture completely masks any layer lines

Painting FDM Prints

PLA requires primer before painting — not for adhesion reasons (PLA accepts acrylic paint reasonably well) but to reveal any remaining layer lines and surface defects. Use rattle-can primer, allow to dry 30 minutes, inspect carefully in raking light, fill any issues with filler primer or putty, then paint as normal with any acrylic system.

FDM prints absorb slightly more pigment than resin on the first coat — your basecoat may appear slightly streaky. Two thin coats of basecoat resolve this.