Brass Challenge Coin: Fiber Walkthrough

A 40mm brass coin with 3D relief image and antiqued finish. Two distinct markets: bulk runs of 50+ (corporate/team orders, $80-150 each) and premium custom singles ($300-400 each, full-cost accounting). The single-piece custom path is for unique commemorative/award work; it doesn't compete with bulk pricing. Total time: ~75-90 minutes engrave + 30 minutes finishing.

The order

"Custom challenge coin for a fire department, fire helmet relief on front, station number text on back."

Materials

• 1× 40mm brass 360 coin blank ($3-8)
• Brass Black antiquing solution
• Fine #0000 steel wool
• Soft polishing cloth + Renaissance Wax
• Magnetic tumbler (optional, for high-volume production)
• 3D-printed coin jig with 40.2mm pocket

Step 1: source the depth map

1. Generate the artwork. Options:
   • Midjourney prompt: "fire helmet relief style, 3D bas-relief, round emblem, simple background"
   • Run image through SculptOK ($) or the free tiling-zoedepth Colab
   • Or render from Blender 3D model
2. Output should be grayscale: white = highest (helmet peak), black = deepest (background).
3. Crop / mask to circle matching coin diameter.
4. Apply 1-2px Gaussian blur to soften step boundaries.
5. Save as 900-DPI PNG at 40mm size.

Step 2: design the back (text side)

1. Vector design with department name + station number + motto.
2. Decorative perimeter (rope or laurels).
3. Save as separate Lightburn project for the back side.

Step 3: customer proof

1. Export both side designs as preview images.
2. Send proof email with both views.
3. Wait for explicit approval. Save proof.

Step 4: setup Lightburn (front / depth-map side)

1. Open Lightburn galvo edition.
2. Place a tool-layer circle: 38mm diameter (engrave area, leaving 1mm rim).
3. Drop the depth-map image. Scale to fit the tool circle (Ctrl+drag corners).
4. Apply Mask to Image (using the tool circle).
5. Image layer mode: 3D Sliced. Critical, without this, no relief.
6. Image layer settings:
   • Speed: 2000 mm/s
   • Power: 85%
   • Frequency: 100 kHz
   • Q-Pulse Width: 200 ns
   • DPI: 900 (line interval 0.008mm)
   • Scan angle: 45° crosshatch
   • Passes: 256
   • Cleanup pass enabled, every 8 passes
7. Cleanup pass settings: speed 3200, power 25%, freq 100 kHz.
8. Add a perimeter outline pass on a separate layer (rope or rim border).

Step 5: load coin in jig

1. Place 3D-printed coin jig on bed. Z height marked on the jig.
2. Drop 40mm brass coin into 40.2mm pocket. Should sit flat with no wobble.
3. Set focus to the marked Z height (use focus stick to verify).
4. Frame with Tool Layers Only. Verify the engrave area lands on the coin.

Step 6: run front engrave

1. Press Start. First 30 seconds. Verify steady tone, no sparks.
2. Job runs ~50-60 minutes (256 passes).
3. Inspect mid-job at pass 100 (if accessible, pause via Lightburn).
4. Air assist running throughout to clear cavity debris (mandatory for relief).

Step 7: flip + run back side

1. Carefully flip coin in jig.
2. Re-focus (the back side has different Z if any warping occurred, re-check).
3. Open back-side Lightburn project.
4. Settings: Fill mode, speed 1500, power 95%, freq 30 kHz, 200 ns, 15 loops, 0.02 line interval.
5. Frame, run.
6. ~15-25 minutes for the back.

Step 8: post-engrave inspection

1. Remove coin from jig.
2. Brush off loose brass dust with soft brush.
3. Inspect under daylight LED at 45°. Check both sides for missed areas, depth consistency.
4. If any issues: address before antiquing (re-engrave specific spots if possible).

Step 9: magnetic tumbler (optional)

1. Place coin in magnetic tumbler with water + burnishing compound.
2. Run 20-30 minutes.
3. Remove, rinse, pat dry. Coin is now burnished, high points polished, recesses still raw.
4. Skip this if you don't have a tumbler; goes straight to antiquing.

Step 10: antique with Brass Black

1. Apply Brass Black solution to entire coin (both sides).
2. Let dry per product instructions (typically 5-15 min).
3. Inspect, coin should now be uniformly dark.

Step 11: highlight with steel wool

1. Use #0000 steel wool to gently rub the RAISED surfaces only.
2. The antiquing comes off the high points, leaving them bright brass.
3. Recessed areas remain dark, creates the antiqued contrast.
4. Don't overdo, keep some patina visible for character.

Step 12: polish + seal

1. Buff raised surfaces with soft polishing cloth or Dremel + felt tip.
2. Apply Renaissance Wax to entire coin.
3. Hand buff with soft cloth.
4. Final inspection, coin should have bright raised areas + dark recesses + protective wax sheen.

Step 13: package

1. Photograph for portfolio (daylight LED, 45° angle).
2. Place in coin display capsule or velvet pouch.
3. Wrap in tissue.
4. Hand-written note + business card.
5. Ship in padded mailer.

Pricing breakdown: single-piece premium custom

Material (coin blank)	$5
Setup time (design + depth map + proof)	90 min × $80/hr = $120
Engrave time (front + back)	75 min × $80/hr = $100
Finishing (antique + steel wool + polish)	30 min × $80/hr = $40
Packaging	10 min × $80/hr = $13
Total cost	$278
Markup (~25-45%)	$72-122
Customer price (single, premium custom) unique commemorative / award / one-of-one piece	$350-400

Pricing breakdown: bulk production runs (50+ pieces)

Bulk pricing assumes a simplified design (fewer passes per coin), template / saved settings, batched finishing, and the design-cost amortized across the run. The 256-pass front-engrave used in the single-piece premium math above is overkill for bulk; corporate batch coins typically run 60-100 passes per side for a 15-25 minute engrave window.

Per-coin material	$5
Setup amortized across batch (design once, run many)	~$2-4 per coin
Engrave time per coin (template / saved settings, ~25 min total at $80/hr)	~$30-35 per coin
Finishing per coin (batched antique/polish)	~$8-12 per coin
Packaging per coin (bulk packed)	~$3 per coin
Cost per coin in 50-piece run	$48-59
Customer price (50 pieces, corporate/team)	$80-150 each

Bulk corporate batches at the LOW end ($80) on a complex coin lose money; only quote $80/each on simple flat-relief designs that finish in <15 minutes engrave time. Anything with deep 3D Sliced detail belongs at the $120-150/each tier minimum.

Common pitfalls

• Depth stalls around pass 100: air assist not running or insufficient. Crucial for relief.
• Background not deep enough: depth map didn't have full tonal range. Re-stretch in Photoshop.
• Antiquing comes off everywhere with steel wool: too aggressive. Lighter pressure.
• Relief looks "flat" under daylight: depth map quality issue: the map is too low in contrast. Regenerate it in SculptOK, or stretch its levels so the tones run from near-white to near-black.
• Coin warping after engrave: heat-affected zone causing slight bow. Use thicker coin blanks (3mm+) to minimize.