For me, its the last details, once its built and finished. glueing hinges, plumbing the tank, mounting the wheels, rigging hthe controls, that stuff is all so fiddly. the Building and finishing seem to motor right along. Once its ready for final assembly it seems to drag for me. The rest is pretty entertaining so I can loose myself in it fairly easily,, ahem, just ask Linda,, many times I get the head out the bedroom door,, "are you coming to bed tonight?" whoops its 11 already,, but not when I am finishing one, especially hinging, I dread it, Always nervous I will screw up all my work by one moment of carelesness. I must admit though I seem to have managed to get away with it so far, my controls seem adequate. I might fiddle with the hinges for two nights before I am brave enough to glue them in.