Export raster DEM to 3D (and 3D print)
To make a 3D mesh model from raster data in ArcMap.
Draw a rectangle defining the area of interest. Keep the dimensions to nice whole numbers like 26x38m.
Select the rectangle.
Right click the raster layer > Data > Export Data.
Set Extent to "Selected Graphics".
Check "Use Renderer" and "Square".
Choose a location, name and set Format to "TIFF". Click "Save".
Open Accutrans.
Go to: File > Open DEM As > Bitmap to DEM > Select the TIFF-file.
Set "Multiplier 2" to "0,5", "Minimum Height" to "0" and "X and Y Spacing" to 1.
Click the 3D-button in the toolbar at the left side of the window.
Take a look at the Min and Max Heights to see if it looks right. With the 0,5 Multiplier from the last step, it appears to be spot on every time.
Set the "Vertex Interval" to something that keeps the Triangle count below 1.000.000 for 3D-printing. Or preferably less, but it of course depends on the purpose of the model. Click "OK".
Rotate the model by depressing the "C Rotate" button at the bottom of the window to see if things look alright.
Now go to "Tools_1 > Adjust Object" which should have appeared in the menu bar.
Type "0,4" into the X, Y, Z boxes. The 0,4 is the distance between the points in the elevation model in ArcMap. Click "Calcualte Scale" to change the model size to anything else. Click "OK".
Click the "Extrude" button in the left-hand toolbar.
Set "Thickness" to -0,5 to give the model a 5mm base.
Select "Flat Bottom". Click "Extrude" and then "OK".
The model can now be saved as "STL" directly for 3D-printing, Collada, 3DS or anything else for further use and post-processing in MeshLab, SketchUp or whatever.