Where to get a fly box for these

[cardiac]

flys and what size hook?
http://magma.nationalgeographic.com/ngm/0305/feature3/index.html

[fishn]

Have you considered a truck box? The large Delta boxes might hold a half dozen and it might look good on your vehicle. On the other hand you might try VERY large chest pack that doubles as a cooler. :-)
fishn/Herb

[Ouzel]

5"!

That would a tye to try. What size hook?

It also might be a little bit of a threat to cast. I know other flies (streamer type) are large but this of course be a Mayfly imitation and the areodienamics would be different.

I guess a box for Orcids might be usuable.