I was thinking about a softbox. The long length should make for a more even distribution of light. Then again I can visualize a giant handle mounted flash to dwarf the Sunpak 622!
Sounds interesting. I would buy a 6 inch white pvc pipe from the local hardware store and cut it lengthwise right in half or a little further and mount the bulb in it with wires or rubber bands and voila, you got a reflector.
A good starting point, and my default, for constructing DIY softboxes for STROBES (ie *not* hot lights) is white foam-core (1/4" thickness) and some sort of diffusion material for the front. You can use tracing paper, drafting vellum, or ideally something like Trans-Lum. Add a good steel straightedge, a sharp utility knife, and some gaff tape, and you're in business.
You could use a "Lite-Brite" toy from the local thrift shop as a housing too.
Tend to be a bit more rugged than foam core.
Still need the diffusing material for the front.