Relief Coin Engraving

3D relief is the fiber's signature trick. Two approaches: (a) 3D Sliced mode: turn a grayscale depth map into sculpted depth, and (b) shovel layer method: multi-level depth from flat vector files. Both produce production-quality challenge coins.

Approach A: 3D Sliced from a depth map

One image, depth modulated per-pixel. Best for organic / sculpted designs. Workflow: depth map → Lightburn 3D Sliced mode → many passes → post-process.

Generating the depth map

Three production paths to a usable depth map, ordered by quality:

1. 3D model render (best quality, most skill). Build / sculpt in Blender, ZBrush, or Aspire. Export a depth pass at the final coin resolution. White = nearest to camera = highest on coin. Black = farthest = deepest. If you can model, this beats every AI tool. The 3D pipeline is "always going to be the king."
2. AI image → depth converter (fastest, no modeling required). Generate the artwork (Midjourney works well, see prompt examples below) and feed the result to a depth-map tool. See the comparison table, pick the right tool because they vary widely in quality.
3. Photoshop bevel-and-emboss (manual). Apply layer style to a flat logo, capture the height map. Decent for simple insignia, weak for organic shapes. Last-resort path.
4. STL you didn't model. Convert a relief STL to a grayscale depth map with a free STL-to-PNG converter (search "stl to png"). White = tallest, black = deepest. Thingiverse, MyMiniFactory, and Cults3D carry many free relief models.

Depth-map tool comparison (community-tested, same source image)

Tool	Cost	Quality	Notes
SculptOK sculptok.com	Paid (~18 credits/download, 100 free credits on signup ≈ 5 free coins)	Best AI option	Returns 4 detail levels in one render. Full tonal spread (bright focal point → mid grays → near-black background). Ring around coin stays uniform, frames the design properly.
tiling-zoedepth (Bill F Smith Google Colab)	Free (runs on Google's GPU)	Free option, decent	One-click Colab notebook, upload AI image, get high-res depth map back. Quality is below SculptOK but solid for general use, and it costs nothing. Best free entry point. See the dedicated walkthrough below.

Image prep

1. Generate or render the depth map at final coin size, 900 DPI (Lightburn sweet spot). A 40mm coin at 900 DPI = ~1417 pixels wide.
2. Remove the background cleanly, clean perimeter cutout matters.
3. Fill AI artifact holes manually (random missing pixels or weird flat regions, especially in AI-generated images).
4. Stretch tonal range so pure black anchors the deepest point and pure white anchors the highest. Full spread is critical. A depth map that only uses the middle 50% of the gray range engraves shallow and muddy.
5. Apply 1-2 pixel Gaussian blur across the whole image, softens hard edges and kills posterization without losing detail.
6. Optional: open in Illustrator and add perimeter text or border (random rune-style glyphs work well, doesn't have to be real text).

Free one-click depth map: tiling-zoedepth on Google Colab

If you don't want to pay per download, there's a community-maintained Google Colab notebook by Bill F Smith called tiling-zoedepth that converts an AI image to a depth map for free. Runs on Google's GPU; no local install.

Prereqs

• An AI image source (Midjourney works best, see prompt examples below). Add the words "bas relief" to your prompt for cleanest results.
• An active Google account, signed in to Chrome.

Step-by-step

1. Generate the source image: Midjourney prompt with "bas relief" gives the best gradient. (No AI access? Search Google Images for "AI bas relief" and use a sample to follow along.)
2. Open the Colab notebook: search "tiling zoedepth Bill F Smith" and pick the latest version (V3 at time of recording).
3. Connect runtime: top-right Connect button → arrow → Change runtime type → select T4 GPU (free tier).
4. Run the notebook: click anywhere in the document, then Ctrl+F9 (Runtime → Run all). An access warning pops up; click "Run anyway."
5. Upload your image when prompted. The notebook then installs all package dependencies, go grab a drink, this takes a few minutes.
6. Output: two files: a low-res preview and a high-res depth map. The high-res version downloads automatically to your Downloads folder.
7. Disconnect when done: click the runtime menu and disconnect. Otherwise Google may temporarily ban you for wasting GPU time on an idle session.

Drop the high-res PNG into your Lightburn coin file and use the same image-prep workflow below. Quality is a notch below SculptOK, expect to do a bit more Photoshop tonal stretching, but the cost is zero.

Midjourney prompts that work

Phrasing that produces depth-friendly images (centered subject, clear focal point, dark background, smooth gradients):

• "boss relief style Viking head with skulls and Viking ship behind it, round emblem"
• "football helmet surrounded by flowers, coin face composition, smooth gradients, clear focal point"
• Keywords that help: relief style, round emblem, coin face, centered composition, smooth gradients.
• Avoid: complex flat patterns, multiple equal-weight subjects, busy backgrounds (depth maps need a clear focal point).

Lens and focus for deep relief

• Use the shortest focal length that comfortably fits the part. Shortest lens = highest power density = fastest material removal. A 40mm coin on a 100mm lens (~70×70mm field) is ideal for depth work. Tradeoff: a shorter lens has a narrower depth of focus (~3mm on a 100mm), just enough for 1-2mm of relief.
• Focus slightly into the material, not on the surface. The beam then reaches best focus partway down, so at pass 100 you are still in focus instead of already past it.

Lightburn setup: the THREE-layer approach (community standard)

1. Tool layer: vector circle the size of your coin's engrave area (e.g., 36.75mm circle in a 40mm blank, leaving a 1.6mm rim). Used for framing only, output OFF when running.
2. Subject (depth map) layer: image mode 3D Sliced. This is the critical setting. Without 3D Slice, you don't get depth modulation, the image renders flat.
3. Border / text layer: vector or image for perimeter detail. Set independently from the subject so you can tune separately.

Setup tips: hold Ctrl/Cmd while scaling the depth map so it scales from center; if the tool circle hides behind the image, drag the image layer to the top of the Cuts/Layers panel temporarily; use Apply Mask to Image to crop the depth map to the coin shape (you can still nudge the image inside the mask); group everything before framing so alignment survives; and turn on Tool Layers Only in Live Framing so the red dot frames the engravable circle exactly.

Verified settings: 60W MOPA brass coin (40mm), community-tested

Param	Subject (depth map)	Border / text
Image mode	3D Sliced	Fill or 3D Slice
Speed	2000 mm/s	2000 mm/s
Power	85-90%	90%
Frequency	100 kHz	45 kHz
Q-pulse width	200 ns	200 ns
DPI	900	1100
Scan angle	45°	45°
Hatch	Crosshatch	Crosshatch
Passes	256	30
Cleanup pass	Every 8 engrave passes	1 final clean pass

100 kHz at 90% is the community-preferred starting frequency on a 60W: smooth background, sharp face detail, no crater texture from over-aggressive low-frequency pulses (see Understanding Frequency).

Cleanup pass (the secret to clean coins)

After every 2-8 engraving passes, run a cleanup pass, a fast, low-power scan that removes vaporized brass dust before it re-deposits on the coin. Without cleanup passes the dust accumulates in the recesses, reflects subsequent passes, and you stall.

Speed	3000-3200 mm/s
Power	20-25%
Frequency	100 kHz
"Clean whole image"	ON

In Lightburn (galvo): layer settings → enable Cleanup, set the cleanup pass parameters above, and pick frequency (every 2 = aggressive cleanup, every 8 = lighter touch). 8 is usually plenty.

Verified variant: the high-frequency fine-slice recipe (60W MOPA)

A second production-proven 3D Sliced recipe for metals, built around faster speed, higher frequency, and a tighter interval than the 100 kHz table above. Where the 100 kHz recipe favors per-pass aggression, this one favors many finer slices, smoother gradients on organic reliefs at the cost of more passes. Both work; grid them against each other on your machine.

Param	Depth layer (3D Sliced)	Cleanup sublayer
Speed	3200 mm/s	3200 mm/s
Power	70%	15%
Frequency	135 kHz	160 kHz
Line interval	0.02	0.03
Hatch	Shapes all at once	Angle 20° / increment 7°, cross ON, bi-dir OFF
Passes	150 min to 600 max, set IN the layer	Clean every 15 passes, "clean whole image" ON

• Set pass count inside the layer, never on the run screen. 3D Sliced is the one workflow where the layer's pass count does the slicing; a run-screen Repeat re-runs the whole slice stack and wrecks the relief.
• Never check Negative Image on a depth map you've prepped white-high / black-deep. If the relief comes out inverted, fix the map, not the checkbox mid-recipe.
• Iterate up, not over. Start at the low end, inspect, then add 30-100 passes at a time until the depth reads right. On ~3mm brass stock, even 600 slices doesn't threaten blast-through.
• Speed floor discipline: keep 3D Sliced work in the 1800-3400 mm/s window on a 60W-class source. Below the window you're slag-welding, above it you stop making depth.

Adjust Image before every 3D Sliced run

Whatever tool made the depth map, run it through Lightburn's Adjust Image (or your editor) with three rules:

1. Gamma: pull until the blacks fully saturate, then back off one click.
2. Contrast: +1. Small nudge, not a crank.
3. No solid pure white anywhere. Pure white in 3D Sliced means "never touch this pixel", so any pure-white region survives as untouched top-surface plateau in the middle of your relief. Knock highlights down to near-white gray.

Settings: anodized aluminum coin blank (40mm)

Easier and faster, you're removing a thin anodize layer plus a skim of aluminum. White-on-color appearance with real depth.

Speed	800 mm/s
Power	50-70%
Frequency	30 kHz
Pulse	200 ns
DPI	900
Image mode	3D Sliced
Passes	30-50

Approach B: Shovel Layer Method (multi-level from vectors)

An entirely different technique. Instead of one depth-mapped image, you stage three vector layers that engrave to physically different depths. Best for graphic / character / logo coins where you want crisp planar levels rather than organic curves.

The three levels of coin design

• Level 1: single subject, single layer. The simplest engrave.
• Level 2: subject + flat background, same depth. Both engrave together.
• Level 3: subject RAISED above a recessed background WITH detail. Real depth, not illusion. The shovel layer method.

Level 2 setup (warm-up)

1. Place the background graphic, then drag the subject on top.
2. Select the subject. Tools → Offset Shapes: distance 0, outward, round, outer shapes only, select resulting object, optimize/simplify.
3. Hold Shift, click the background. Tools → Boolean Assistant → Subtract B-A. Background now has the subject's silhouette punched out.
4. Move the subject onto the same color layer as the background. One layer, two graphics. Run.

Level 3: the shovel layer setup

1. Build subject + background. If subject has multiple disconnected pieces (main figure + floating accents), Boolean Union them two at a time until they're a single shape.
2. Tools → Offset Shapes on subject: distance 0.1mm (the rim around the subject, keeps the wall clean).
3. Hold Shift, click background. Tools → Boolean Assistant → Subtract. Background has subject's offset silhouette punched out.
4. Create a new fill layer: a circle the SAME size as your engrave area. Call this the shovel layer.
5. Group subject + background to keep them aligned.
6. Drag the shovel layer in. Select all. Click bullseye align, everything centered on the same axis.
7. Ungroup. Hide background visibility for clarity.
8. With subject selected: Tools → Offset Shapes again (same 0.1mm, exact same value as before).
9. Hold Shift, click shovel layer. Tools → Boolean Assistant → Subtract. Shovel now has subject's silhouette punched out, matching the background.
10. Move shovel back to its color. You now have three aligned layers: subject, shovel, background.

Level 3: engrave sequence

Output OFF on all layers except the one you're running. Run them in this order:

Order	Layer	Output ON	Passes (example)	Effect
1	Subject	Subject only	50	Engraves subject at top surface (slight relief)
2	Shovel	Shovel only	100 (≥ subject passes)	Recesses the area around the subject deeper
3	Background	Background only	80	Engraves background detail INTO the now-recessed floor

Result: subject sits proudest at the original surface, shovel created a recessed plane below it, background detail is etched into that plane. Three real depth levels from flat vectors.

Post-processing (the part that sells the coin)

The engrave is only half the work. Coin finish is what makes a $40 challenge coin look like one.

Standard workflow (light to medium relief)

1. Magnetic tumbler: water + burnishing compound, 20-30 minutes. Burnishes the high points to a shine, doesn't touch the recessed areas. JX-185 (~$80-150) is the budget standard; Sunsheen / KT premium ($200-400). Pair with stainless needle media (1-2 lbs) and Sunsheen Quik Sparkle compound.
2. Brass Black antiquing (Birchwood Casey, ~$15), apply with brush or cotton swab, let dwell 30-60 seconds, rinse with water. Darkens all surfaces uniformly via selenium-dioxide chemistry. Wear nitrile gloves + eye protection (it's classified as poison).
3. Steel wool (fine, #0000): gently wipe the raised surfaces. Removes the antiquing from the high points so they shine bright; recessed areas stay dark. This contrast is what makes the coin look authentic.
4. Dremel + felt polishing tip: buffs the high points to a mirror shine.
5. Renaissance Wax: apply, hand-buff. Locks in the finish, prevents oxidation, gives a soft satin glow.

Heavy relief: the paint-fill upgrade

Brass Black is chemistry-based, it stains the metal SURFACE but doesn't fill physical depth. On heavy relief (1mm+ deep recesses), light still bounces around inside the cavity and the coin can look "shallow" despite the dark chemistry. The fix: combine Brass Black with paint-fill so the recesses are PHYSICALLY filled, not just stained.

1. Magnetic tumbler burnish as in standard workflow.
2. Brass Black as the base layer, covers the recess walls in dark chemistry. Don't wipe high points yet.
3. Black acrylic enamel paint (Testors Model Master, Apple Barrel Black, or Rust-Oleum Specialty Enamel), work into the deep recesses with a small detail brush (size 0-2). Press the bristles down into the cavity to ensure the paint reaches the bottom. Don't worry about getting paint on the high points.
4. Wipe high points while paint is still wet. Soft microfiber cloth lightly dampened with denatured alcohol or acetone removes paint from the raised surfaces but leaves it filling the recesses. Work in straight strokes. Don't scrub circles.
5. Let dry 24 hours. Acrylic enamel needs full cure for durability.
6. Polish high points with Dremel + felt tip OR a soft cloth. Brings the brass to a bright shine while paint stays protected in the recesses.
7. Renaissance Wax seal: final protective coat over everything.

Why paint-fill outperforms Brass Black alone on heavy relief

• Physical depth fill: paint occupies the recess volume; light hits a flat black surface instead of bouncing around inside a cavity.
• Universal substrate: works on brass, copper, nickel-plated steel, aluminum. Brass Black only works on copper-based metals.
• Reapplyable: if paint chips or wears, re-apply locally. Brass Black requires re-stripping the entire coin to redo.
• Better photographic contrast: paint-filled coins photograph far better for marketing / Etsy listings.
• Tradeoff: paint can chip with rough handling. Renaissance Wax helps. For heavy daily-use coins, chemistry alone is more durable.

Paint-fill shopping list (~$20-30)

• Black acrylic enamel paint (Testors Flat Black or Apple Barrel Black), $4-8
• Detail brushes, sizes 0-2 (cheap craft store set), $5-10
• Denatured alcohol or acetone, $3-6
• Microfiber cloths (10-pack), $5
• Disposable nitrile gloves, already in your safety kit

Materials and where to source

• Brass 360 (free-machining brass): sharpest detail, takes brass black antiquing perfectly. The default for premium coins.
• Copper: warmer color but reflective; needs slower speeds and more passes. Dramatic finished look.
• Nickel-plated steel: silver appearance, easy sourcing, magnetic (jig with magnets). Cheap blanks for prototyping.
• Anodized aluminum: fastest turnaround, white-on-color, no antiquing needed. Good for batch jobs.
• Avoid mirror-polished blanks for relief work, every scratch shows, and the reflectivity throws the beam.

Jigs

• 40mm coin: 3D-printed PLA tray with a 40.2mm pocket, 0.8mm deep. Magnetic base for steel blanks.
• Multi-up tray: 4-up or 8-up. Lightburn array-fills the layout and runs all in one job.
• Engrave both sides of a 2-sided coin in one session, Z calibration drifts overnight, and you'll see a misalignment between sides if you split the job.

Sources: community YouTube walkthroughs on AI depth-map coins, the shovel-layer method, and 3D Sliced coin work; settings tested on 30-60W JPT / OMTech MOPA sources and cross-checked against community 100W brass-relief posts. Starting points only, always run a test coin.