I have always struggled with lighting for my miniature photography, and decided to go with making my own DIY LED ring light after seeing this instructable:
It took me about half an hour to put it together as I had all the items at hand, but it was an ad hoc project, forgive the little boo-boos!
25cm (or 5 x 3-LED light segments) 12V LED Light strip (Bright white, available from ebay)
1 x Battery Holder for 12V 23AE sized batteries
1 x Self Locking 6 Pins Torch Push Button Switch (available from ebay)
1 x 12V 23AW battery
1 x plastic sauce container cover (9 cm diameter)
Soldering Iron (30W, my 60W wouldn't work today :( )
0.3mm, 1mm soldering lead
3rd hand soldering stand
Double sided Tape
I think the hardest bit would be waiting for the light strips/battery holder/switch to arrive from ebay, but I had everything lying around as I build miniature roomboxes and stuff. This project cost me no more than USD$10 to put together.
I opted to go with a disposable sauce container lid, approximately 9cm diameter wide, as it was thin and sturdy enough to fit between my lens and the lens adapter.
Using a circle cutter (from Daiso), I measured the inner diameter of my favourite lens (EFS 18-55mm) and cut out a circle.
Test fit it against the step down ring adapter that I use for my macro clip-on lenses (had purchased the wrong sized clip-ons hawhaw -_-" ).