Hi Felix - so that boolean problem looks like a bug, something is getting mangled in the calculation of the intersection curves between the pieces. I'll put it on my list to investigate.

But it also looks like a contributing factor is the relatively small size of the objects - smaller sized objects can tend to make the booleans job harder - I'd suggest building your objects to be around a factor of 10 larger in size instead of so small.

For example here I've attached a version of your file and all I did was scale it up by a factor of 10 times in size and move them closer to the origin and it seems to boolean together ok now.

It can tend to confuse the booleans when you have small features which start to approach the 0.001 fitting tolerance, it will try to do things like combine intersections together that are within that distance of each other and that can sometimes have a tendency to disrupt the boolean process, something like trim loops get portions of them collapsed down and make an invalid loop.

In your original file there you've got spheres that have a radius of 0.06 inches - basically try to avoid making individual features which are small enough that they're measured in hundredths, try building things at more around 10 times larger than that at a minimum and you'll probably avoid a lot of problems.

- Michael