Actually I made this first thingy already some time ago, but I'm trying to centralize all my tinkering into ATM now.

1. Flash mirror

This simple thingy I made out of piano-wire or spring steel wire + a small piece of plastic mirror. The wire I used was 0,8 mm dia (1/30") and the mirror material is some stuff meant for car mirror repairs available from Biltema. The wire frame slips in place through the flash and flash hot shoe gap. Once it's in the flash shoe, it will be held in place by the flat springs there are under the hot shoe's edges.

I made the mirror too small at first; although it seems that the flash is completely blocked by the mirror, there's considerable amount of light leaking around the edges ---> the bigger the better. It helps a lot getting the mirror as close to the flash as possible, as seen in the two sample pictures (only difference is the mirror-to-flash distance).