If you just want a big bright flash.

Take a cardboard box, open on one end, wrap it with plastic wrap (the food wrap kind) including the open end. Purge the atmosphere from it with xenon gas. Attach a small explosive to the side opposite the open end. Detonate at will. These things can be sized to provide flashes with enough power to do real damage.

I saw these being used on an explosives test firing table. This type flash was needed to provide enough light for the high speed cameras. Some of them have shutter speeds >10ns, and need massive doses of light to get an image.

Glenn

Warning: Do not look into bright light with remaining good eye!