I do not regularly make PC board exposures any more now that Alberta Printed Circuits exists......But a colleague of mine showed me a long time ago that normal outdoor sunshine on a bright day works very well for home project exposed PC board artworks. If you make your self an exposure frame with two pieces of 1/4 inch thick glass hinged together in a manner to very firmly hold the art film against the photo resist on one or both sides of your PC board blank. Don't forget to make the artwork films with the emulsion on the side that hugs down to the photo resist so you prevent light from sneaking in under the dark areas of the artwork. Note it is even possible to make your artwork films in a laser printer by printing onto transparency sheets. But you have to be willing to live with some pinholes in your PC board etches if you use the laser printer scheme.
Mike Karas