Thanks Electroglyph - that was the solution. You saved me from the fate worse than death (Reading The..............)! Drawbridgep - not quite - I don't want the centre hollow, just passages running through. Now that I've been able to position the primitives properly I can see that it's a crap idea, and would look as ugly as hell :o( Back to the drawing board. I'll keep plugging away to see if I can get it to look a bit less like a bowler hat.