I'm warping the loom to weave a set of patterned cloth napkins. A 20" napkin x 24 ends/in = 480 individual threads. These are threaded through metal heddles in a particular order to make the pattern. Imagine threading 480 needles but which needle you pick next *really* matters.
Update: I finished threading the heddles. It took me about 5 hours total. This is why I'm making a set of 8 napkins, not just one at a time--the up front work to "dress the loom" is the same regardless of how long the warp is.