Monty is dead on with the Transfer punch set, an invaluable tool, and all that is needed for nearly any disassembly. The only important thing they can't do easily right out of the box is remove a 7mm transmission easily, but if you can drill a 7mm hole in a block of wood, you can get that done too...
As for assembling,I made a set similar to this:
and love it for assembling pens by turning the MT2 and flat press area out of scrap (doesn't have to be a perfect MT2, as you will not have your lathe on when you use them!!!:tongue
It gives you MUCH more precise control over how far you press things in (great for those 7mm transmissions in odd sized barrels...) than any of the hand presses I've used...