2. Add boundary condition in CAD, here is using FreeCAD software. You can use other cad software, (i.e. SolidWork, AutoCAD, ...)

In FreeCAD, "Create a 2 point rectangle", to create 2D point plane

here define the boundary : X= 37 mm, Y=15 mm, Z=40 mm

(Linux system need to fix "Make Face" properties from "false" to "true")

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Due to the default setup of "Make Face" of "Create a 2 point rectangle" function of FreeCAD in Linux system is false, this will leads to the transparency boundary and export wrong stl file to FonSinEM.

You need to change the value from "false" to "true" of Make Face of of "Create a 2 point rectangle" function.

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3. export the cad file with boundary condition to *.stl

4. Open FonSinEM 3D CAD - following the step below,

5. Check the created grids, you can change the delta (dx, dy, dz) to tune the resolution.

Off course, the higher resolution will require longer calculation time.

Be carefully, the order of import *.stl CAD file, the upper side cad material will be overlapped by lower side cad material

About the FreeCAD Problem

if there are two cad material overlapped and output in the same CAD file. Like this example : Cross_With_Boundary.stl

Then, if directly output these two cylinder structure, the part of overlap may caught some error in create FonSInEM grids. This is due to the mesh discontinue in these two CAD

Here can use the function of FreeCAD "Make a union of several shapes" to solve this problem, then the mesh will combined at one.