Hollow model without overhang roof

Say I have a flat top “home” model that is a solid, I can shell get rid off the floor and make 5mm thick wall.but it will have roof overhang that cannot be 3dprinted.
Easy option is obviously slid the roof part off and print separately. But if it is a complicated geometry solid object,and I do want to keep inside hollow or at least reduce inside volume,

how do I get it easily in rhino? I currently create cones and place them from floor. and boolean split from main object.it works, but
1, it is too slow process, too much manual, 2, it wasn’t able to get rid off all possible material.
Another option is shell first with thick wall, then “boolean” off the thickness from lower walls.

The optimum solution is create a internal sharp dome, resembling outer geometry, but keep the top part non-overhang.

Well, if you don’t have too many, you can:

  1. Extract a copy of the roof surfaces, join back together. ( I assume here a std. peaked roof)
  2. OffsetSrf (Solid=no) the roof copy downward the desired wall thickness, delete the original.
  3. DupFaceBorder the bottom of the “house”.
  4. Offset the bottom outline you got above towards the inside by the wall thickness
  5. Extrude (solid) the offset outline all the way through the roof
  6. BooleanSplit the extrusion with the offset roof; delete the unwanted parts
  7. Boolean difference the inner volume from the house.

Another quicker and slightly dirtier way to do this:

  1. DupFaceBorder the bottom of the house as above
  2. Offset the border to the inside as above
  3. Extrude the offset (solid) all the way through and a bit above the roof
  4. BooleanSplit the extrusion with the house; delete the upper part
  5. Ctrl+Shift+Pick the upper surfaces of the volume you just split (sub-object selection)
  6. With Gumball or nudge keys, move the surfaces downwards a value of something larger than the wall thickness (like 1.5-2 times)
  7. BooleanDifference the volume from the house

In the second case, the wall thickness at the roof will not be necessarily uniform or exactly what you want, but it might be good enough. The second operation I can do in about 30 seconds for one object.

Still pretty manual, part of it may be able to be script-automated, but maybe it helps.


Might be a silly option, but if you don’t need a floor and it’s single story, once you hollow the house, print it upside down, the overhang shouldn’t be an issue.

Best regards,