Hi Nick - re: booleaning letters on the sphere - from what you wrote it sounded like you were projecting curves, then extruding the projected curve? You'll end up with a non-planar curve that way and extruding a non-planar curve will not produce end caps because the curve extruder only knows how to put end caps on planar curves.

But if you use Trim to cut up the sphere surface by your curves, you can instead extrude those smaller surface pieces, and extruding a surface will always result in end caps even if it is non-planar because the extruder knows it can just make a copy of that surface on the other side to cap it off.

So if you do it that way (extrude surface pieces rather than curves) you'll have solids after the extrude and you won't have to do some of your other steps after that.

Another tip - you may want to use the Shell command on those surfaces to thicken them up rather than extrusion - the shell command can take a surface and then produce a thickened solid from it and you don't have to set any direction for it because the it's created by surface offsetting where it follows the surface normal of the starting surface.

See here for an example image for Shell:
http://moi3d.com/2.0/docs/moi_command_reference7.htm#shell

- Michael