Solid box within solid box boolean difference Objects do not intersect. Nothing done

wishing to make a box with 3mm thick walls I create a box using solid box tool then offset srf 3mm.
Boolean Differnce command, choose outer then inner and it fails.
Objects do not intersect…nothing done it says.
why cant I boolean difference this using the inner one as the ‘cutter’, surely it intersects as its inside !

I am having to make boxes up in rhino to estimate box weight for ebay selling as its not practical to go running about to supermarkets getting boxes incase the item never sells, and listings require box size and weight, and postage costs, all before it sells, if ever. Pain in the %$£&.
so use spec gravity of my cardboard and knock out a quick box in rhino then add flaps etc, and padding.

boolean difference fails on box within box.3dm (52.8 KB)

Hi Steve,

There are dozens of ways to do this, I would recommend making the suface, extruding it and then copying it over or making the rectangle in plan, offsetting it and then extruding that by your desired measurements.

See attached file.3MM Box.3dm (334.7 KB)

Why not just find the surface area of the outside of the box and multiply it by the weight of a square cm of the box material?

Aside from the other answers, plus simply getting the volume of the two boxes and subtracting them, you can actually make a hollow box that will give the correct volume.

Make the outer box and the inside offset box. Select the two boxes and call _NonManifoldMerge followed by _CreateRegions. That will leave you with two volumes, the inside box (delete that) and the hollow box - use that to get the volume.

HollowBox.3dm (413.4 KB)

you really dont need to create a 3d model for that… only if its some complex shape which is being milled out, the rest would be just plain procrastination :wink: