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Material options

	METHOD	MATERIAL	COST ($/sf)	TIME: file prep (hr)	TIME: fab (hr)	TIME: assembly (hr)	TIME: total	MATERIAL RECYCLABILITY
	Horizontal laser-cut topo - 25 layers	1/16" chip with plywood base	$30	8	5	10	23	yes
	Horizontal laser-cut topo - 25 layers	4ply museum	$62	8	5	10	23	yes

File preparation

1. You'll need a file with horizontal contour lines at a vertical spacing that matches the thickness of your modeling material.
   
   1. If your base file contains contours at a different resolution, use the RhinoTerrain plugin (available in the Software folder on Goliath) to make a 3D mesh from the given contours.
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   2. You can either:
      1. Contour the mesh and the buildings
      as shown and then
      1. together,
         1. Then clean up the resulting contour curves (delete building contours
      Use
      1. 1. which are below the surface of the topography, and remove topography curves which are inside buildings).
            
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      2. Or, use the drape command to create a NURBS surface from the topography mesh,
      trim out the areas of overlap, and then contour (less cleanup required).
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      1. 1. Then use the buildings to make holes in the new NURBS surface,
         2. And use the new NURBS surface to trim away the subterranean parts of the buildings.
         3. Then contour it all together. By trimming the surfaces, you avoid having to trim the contours as in option (i).
            
            
2. Put the resulting contours on your CUT layer, then copy them up (along the positive Z axis) one level. Put the copies on your ETCH layer.
   
   
   
   
3. Lay out each layer pair (one CUT, one ETCH) on laser bed-sized (18" x 32") sheets of material. Small layers can be nested inside larger ones to save material.
   
   
    
   1. Label your sheets to keep track of stacking order. 

Making the model

1. Prepare material for the number of sheets you will need to laser cut. 
   
   1. If buying material from the GSD Store, it will already be cut to the laser bed size.
   2. If buying material from other vendors, you most likely will need to cut material to the laser bed size (18" x 32").
2. Always test cut a small piece first to make sure that the laser is cutting the material through all the way. The edges of the cut sheets will be very visible, so use as low of a PPI setting as possible to minimize burning. 
3. Once all sheets have been cut:
   1. Stack layers in order, aligning the top layer to the ETCH of the bottom layer.
   2. Glue layers together 
      1. Spray mount adhesive works best for fast assembly.
      2. Only spray on the bottom (non-visible) side of each layer to avoid messy craftsmanship.   

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