Lorenzo asks:

And he has no idea that he's just written a blog entry for me.  Thanks Lorenzo!

Probably easier to get out of the basement in springtime, too.  (man, who put a nickel in me today??)

Okay
– it seems to be a rigid heddle.  Look closely at the fancy wooden
piece – see how there's slots, BUT look, between the slots there's
bitty bitty holes, with threads running through?

So, if in an ABABABABABAB simple alternation sort of pattern, where
A is slots and B is holes, if you pull the whole heddle up, the threads
strung through the B holes will come up with the heddle, whereas the A
threads will stay level and somewhat slacker.  This makes the magic
shed, where you put your shuttle with weft through.  Then if you push
the heddle down, the A threads steadfastly stay level, and those
easily-influenced B threads make the reverse shed underneath – pass the
shuttle again.  Ta da – tabby weave!  Which seems to be what she's got
there, in a repp sort of structure (repp = fat weft, skinny warps, warp-faced,
think rag rugs, but also Anglo-Saxon linen tunics).

Notice that the A threads are mostly white, and the B threads are mostly blue?  Very clever.

Since she's calling it a backstrap loom, that means she's tying one
end of the warp to a stationary something, and the other to herself,
and controlling tension via her body positioning.  You could use the
same rigid heddle with two stationary tieoff points (like C-clamps on a
board, a personal favorite, admittedly Not So Pretty but
cheapcheapcheap).  Or a bee-you-ti-full box loom of some variable design, so long as it had Ways of Controlling Tension.

If you are making this heddle, be sure the slots are tall, parallel
and smooth – you want the A threads to slip easily up and down, and to
have a tall shed through which to pass the shuttle.  The slots on the design above look a bit fatter in the middle – this is probably a Good Idea, as even the smoothest yarns have microscopic velcro hooks on them and they sometimes need to be encouraged to separate into their correct sheds.  Like soap opera plots, this is helped by a healthy amount of tension.

Have fun!

(note to the general public for geekiness – a 'rigid' heddle is one that's formed out of something that isn't a bunch of ductile stuff strung together, like a frame with string heddles, or clackety metal heddles, that all slide around.  Rigid heddles set up your spacing for you somewhat, whereas more complicated loom structures do that separately via a comb-like structure called a 'reed'.)