as promised i finally got to write a very small how-to on making your own inexpensive (50€) ring light for video and stills (most suited for indoors since it is cable-bound and not weather proof).
step 1: buy a lamp with a circular tube (see below). those you can get at any hardware store (got mine at bauhaus jägerstraße in vienna if you are a local). some of them are around 100€ because they have reflectors and glass covers. the one that i found and used here does not have all those things and therefore was comparatively cheap.
this is what the lamp looks like:
step 2: since i want to view through the ring towards the model i need to somehow separate the lamp base from the tubes and rotate them up. in this case it was easy as can be because the fluorescent bulb is just clipped onto these two plastic holder that you see there. the third one i secured with tape so the ring does stay in position once i move it up.
step 3: the lamp is of course made to be connected to your ceiling, not a power socket, so just was two cables hanging out of the back side. to make it into something i can plug in i sacrificed an old computer cable and soldered it to the wires. this allows me to use another standard power cable and just plug it in without the clutter of having the cable constantly dangling below the light in case i want to transport it.
if you don't feel comfortable doing the soldering yourself ask an electrician friend to do this for you. this should be done properly! i secured the cable with some tape which looks a bit like a hack but so far it works fine.
step4: plug it in, shoot away and have fun with it. here's a quick mugshot made with this lamp