CNC + Laser: Topographic & Lake Maps

Topographic and lake maps are one of the highest-margin CNC + laser combos. The CNC carves the actual elevation contours from real terrain data, every ridge, valley, and lakebed in physical depth. The laser adds the labels, borders, dedication text, and compass rose. The result is a wall piece that says "this is the real shape of THIS specific place", and customers will pay $200-500+ for a personalized one.

Where to source the elevation data

You need a Digital Elevation Model (DEM), a grayscale image where pixel brightness = elevation. Three free / cheap paths, ordered by skill required:

Workflow: full pipeline

1. Pick the location and frame size. Standard sizes: 12×12", 16×20", 18×24", 24×36". Square frames suit lakes; rectangular suits coastal/regional terrain.
2. Pull the DEM. Touch Terrain or USGS for the area. Set resolution so 1 pixel ≈ 0.5-1mm on the final piece (i.e., a 12×12" piece at 300 DPI = 3600px wide).
3. Process the depth map in Photoshop:
   • Stretch tonal range (Levels) so highest peak = pure white, lowest valley = pure black. Like depth-map prep for relief coins, full spread is critical.
   • Mild Gaussian blur (1-2px) to soften terraced steps from low-resolution DEM data.
   • Optional: paint a hard-edged mask for the lake outline so the water area is solid black (deepest cut), giving a clean basin for epoxy fill later.
4. CNC the elevation. In Aspire / Vectric / Carveco: import as a depth map, set max cut depth (typically 6-10mm for a 1" thick blank), use a 1/8" or 1/4" ball-nose for the roughing pass + a 1/16" tapered ball-nose for the finishing pass. 4-8 hour cut depending on size and detail.
5. Sand the carved terrain with 220-grit on a flexible foam pad, knocks down fuzz from the CNC without flattening the contours.
6. Move to the laser. Engrave the labels (city names, lake names, peak elevations, coordinates), the border / frame, the compass rose, and any dedication text. Use the same T1 Tool Layer / sacrificial-outline alignment from the plaque module.
7. Optional epoxy water pour (lake maps), see below. The killer feature.
8. Finish: Danish oil + wax, or a polyurethane satin if it'll be hung in a humid environment.

The epoxy water pour (lake maps only: the premium upgrade)

If your map includes a lake, the CNC has carved a basin where the water should be. Filling it with tinted clear epoxy creates an unmistakable "actual water" effect that pictures can barely capture.

1. Engrave first, pour second. Resin over engraving = engraving disappears. Engraving over cured resin = laser doesn't mark resin cleanly.
2. Seal the wood in the basin with a thin coat of clear shellac. Prevents the epoxy from soaking into the wood and going matte.
3. Dam the perimeter with hot glue or painter's tape if there's any chance of overflow.
4. Pour deep-pour epoxy (1-2" max per pour, pourable like Stone Coat Countertops, Total Boat MakerPoxy, or Liquid Glass) tinted with a few drops of translucent blue/teal pigment. Mica powder for the shimmer if you want.
5. Heat-gun lightly to pop bubbles, then cover and let cure 24-72 hours.
6. Sand flush with 220 → 400 → 800 grit if any epoxy bled past the basin lip. Polish to gloss with 1500-3000 grit if you want mirror-flat water.

Materials & substrate choices

• Baltic birch plywood: cheapest, no grain to fight, takes detail. Best learning material.
• Hard maple: premium light wood, fine grain, takes the laser cleanly.
• Walnut: dramatic dark base for light-engraved labels. Premium look.
• Poplar: cheapest hardwood, paints well if you want a colored topo.
• Layered acrylic stack: radically different aesthetic. Each layer = one elevation contour, stacked. CO2 cuts the contours as flat profiles instead of CNC carving.

Pricing reality

Lakes near major metro areas (Tahoe, Powell, Norris, Lake of the Ozarks, Smith Mountain Lake) consistently sell. Wedding-venue locations and "where we got engaged" maps are the highest-converting custom orders.

Common pitfalls

• DEM resolution too low. A 30m USGS DEM on a small lake gives terraced "stepped" contours. Use 1/3 arc-second (~10m) or finer; for very small areas, lidar-derived DEMs from state GIS portals.
• Tonal range not stretched. Half the depth gets compressed into the middle gray range and you lose ridges. Always anchor pure black + pure white in Photoshop.
• Engrave bleeds onto carved contours. Labels placed too close to terrain features get engraved into a sloped surface and look smeared. Keep all labels in flat zones (border, lake surface, low-relief plains).
• Epoxy soaks into bare wood. Always shellac-seal the basin first.
• CNC and laser files not registered. Same master-file discipline as the plaque module. One file, two outputs.