Check out photographer Don Brice‘s excellent modification that allows you to use normal flash/strobe units on Diana toy cameras:
I enjoy using the Diana in the studio and shooting portraits and still life lit with flash. I discovered long ago that by ripping off the usual connector on the end of the syncro cable, you could bare the two wires and jam them down the two flash sockets on the Diana-F model. Ta-da. Plug the other in to your strobes and away you go…
Continue reading instructions at Brice’s blog, Blurry Thinking.