Brian Lawson fired this volley in
:

I don't know what it is called, but this sounds like the perfect job
for the form of a tape measure blade, where when straight, the "blade"
is concave (or is it convex??) across its width and wants to stay
"straight", and flat when coiled. I haven't seen one for quite some
time, but there used to be short rules say 1" wide of 24 or 36" length
that were "loose" and not inside a tape measure that worked that way.


That's the essence of what we're doing, except plain carbon spring steel
is not acceptable. This item will never un-reel, except for a
'standout' piece about 3" long from the body of the coil. The coil will
simply unwind to a slightly larger diameter from its rest condition. The
rotary element is constrained to 355 degrees of rotation.

It cannot be coiled tightly, because there must not be the chance of
crushing explosive particles between layers. It's ok to get them between
layers, but there's a limit on the force allowed. The stuff doesn't
stick to metal, so as long as it's not crushed, it is 'self cleaning' in
that respect.

Lloyd