Hi MA,

> I have been trying to subtract a solid from a bigger one as per the usual Bool
> Diff command. However, this merges the two solids into one instead! I am
> baffled and cannot figure out how things might have gone wrong. Any clues anyone?

When this happens it means that MoI has not been able to determine which direction is the outside direction of the solid. The most common cause is having curves that criss-cross back over themselves making a self-intersecting area. Such self intersections can interfere with solid volume calculations.

Thanks for posting the file, I'll take a look and see if I can figure out where the problem is at, my first area of focus would be looking for self intersections in the illustration geometry.

- Michael