I drew a 3D diagram with blender software.Export to obj format,It is then added with simplegeo software, but the output to fluka is not recognized.Curiously, simplegeo software can implement viewing!
Obj is a polygon based surface modeling format which currently has no equivalent in FLUKA. Therefore, you cannot export it properly to FLUKA even though SimpleGeo supports OBJ.
For the model that you are showing it is probably the easiest to directly model it in SG or geo viewer by cloning RPPs.