Laser Cutting Construction Kit

For this project, I designed a parametric construction kit with interlocking pieces that account for laser kerf. The kit demonstrates print-in-place principles where individual pieces slot together without additional fasteners or assembly.

Design Tools & Materials

Design Process: Parametric Construction Kit

Step 1: Source Design Image

The design process began with a Frozen movie ice motif image, downloaded as inspiration for the decorative engraving element.

Source image: Frozen ice pattern for construction kit engraving.

You can get the image from here

Step 2: Convert Raster to Vector

The JPG was imported into Inkscape and converted to vector format using Path → Trace Bitmap. This created clean, scalable paths suitable for laser engraving.

Vector paths extracted from raster image—ready for laser engraving.

Step 3: Import SVG into Fusion 360

The SVG file was imported into Fusion 360 as the central decorative element. Two concentric circles were drawn around it to define the structural boundary of each kit piece.

Fusion 360 sketch showing engraving motif and structural geometry.

Step 4: Define Parametric Parameters

Parameters were created for key dimensions: material thickness, kerf, compression, and slot width. The slot width was calculated as: Slot Width = Material Thickness − Kerf − Compression

To add parameters, select Modify → Change Parameters, then click the plus button to create new parameters.

Parameters dialog showing material and tolerance values.

Click the plus button to add new parameters.

Parameter entry dialog.

Parameter list showing all dimensional constraints for the kit.

Step 5: Create Slot Geometry

A center rectangle was created with:

• Width: Calculated slot width parameter (2.65mm)
• Height: Material thickness (3mm)

Using Create → Circular Pattern, multiple slots were arrayed radially around each piece, creating a symmetric pattern for interlocking assembly.

Step 6: Complete Design & Extrusion

Additional decorative elements were added, and the entire sketch was extruded to create 3D geometry. The extrusion depth was set to match material thickness.

Then I added new designs.

Completed construction kit design with parametrically-defined slots and decorative engravings.

Step 7: Project Components onto a New Sketch & Export as DXF

With all components designed and arranged in 3D space, the next step was to prepare the flat cutting profiles for the laser cutter. This involved projecting the 3D geometry back onto a 2D sketch plane and exporting in a format the laser cutter software can understand.

1. Create a new sketch on the XY plane (or any flat reference plane that aligns with the material surface)
2. Modify → Project/Include → Project (P shortcut in Fusion 360) to project the body edges onto the sketch. Select all relevant faces — outer boundary, inner slot edges, and any decorative cut lines
3. Verify the projected profiles: Confirm all slots, circles, and cut paths appear correctly as 2D sketch entities with no gaps or overlapping geometry
4. Finish the sketch once all profiles are cleanly projected

Exporting as DXF

Once the projected sketch was verified, the design was exported as a DXF (Drawing Exchange Format) file

1. Right-click on the sketch in the browser tree → select Save As DXF
2. Choose a save location and filename (e.g., construction_kit_v1.dxf)
3. Fusion 360 exports all sketch geometry as 2D vector entities: lines, arcs, and circles

This design was abandoned cause the instructors warned me that the design cuts will be too small. So I made a test cut instead.

It ended up burning. So I abandoned the design.

Then I went and design a new one.

Step 8: Inkscape Workflow — Preparing the DXF for the Laser Cutter

With the DXF file exported from Fusion 360, it was imported into Inkscape to prepare the final cut file. Inkscape acts as the bridge between the CAD design and the Trotec laser cutter, allowing line colors and stroke properties to be assigned so the machine knows which paths to cut and which to engrave.

1. Import the DXF File

1. Open Inkscape → File → Import (or drag and drop the DXF file)
2. Select all components (Ctrl+A)
3. Press Ctrl+Shift+R this fits the canvas exactly around all imported components

2. Verify Scale & Dimensions

1. Select all geometry (Ctrl+A) and check the width/height in the toolbar, they should match the designed dimensions exactly
2. If dimensions are off, use File → Document Properties to confirm the document unit is set to mm

3. Assign Line Colors for Cut vs Engrave

The Trotec laser cutter reads line color to determine the operation type. Each color maps to a separate job in Trotec JobControl with its own power and speed settings.

4. Group & Arrange Components

1. Select all cut-line geometry → assign red hairline stroke via Object → Fill and Stroke (Shift+Ctrl+F)
2. Select all engraving geometry → assign black fill
3. Arrange all pieces within the material boundary — keep a 5–10 mm margin from edges
4. Nest pieces efficiently to minimize material waste

5. Print to Trotec JobControl

1. Go to File → Print (Ctrl+P)
2. Select Trotec Engraver as the printer
3. Click Print — this sends the job directly to Trotec JobControl
4. In JobControl, the cut lines and engrave areas appear as separate color-coded layers, each assignable to power/speed profiles

Machine Setup & Focusing

Adjustable Bed System

The Trotec laser cutter has an electronically controlled adjustable bed that moves vertically using internal motors. The focal distance between the laser head and material is critical for cutting accuracy.

Adjustable bed raises/lowers to maintain precise focus distance.

Control panel showing bed movement controls.

Focus Calibration (Critical for Precision Cutting)

1. Place material on the bed
2. Use up/down buttons to position bed approximately
3. Use the Trotec focus gauge (official focus tool) to set exact focal height
4. Adjust bed until focus gauge just touches the material surface—this is the focal point
5. At correct focus, laser beam converges to minimum beam diameter for optimal cutting

Cutting Parameters

After the file is sent from Inkscape to Trotec JobControl via the print dialog, each color layer appears as a separate job entry.

Parameters Used for This Job

Cutting Results

Once the file is prepared and machine is focused, the laser cutter executes the digital design, cutting all slots and engraving decorative elements in a single operation.

Prior to cutting the final design, a test cut was executed using a separate file.

After the test was successful, I went for mass manufacturng.

I arranged the design below by copying and pasting by hand.

Arranging Components with Fusion 360's Arrange Function

Instead of arranging components manually, Fusion 360 provides an "Arrange" function that automatically positions components on a flat plane.

You can go to Modify --> Arrange

Arrange only works on components, not bodies. Before using it, each body in the design must be converted to a component:

I did not use arrange function in my workflow. Instead I arranged the components manually.