There are many solutions available to expose the photo-resist of a PCB and I want to share mine, only pcb described here and CAD files given. Module сan be used as is or in self-made housing.
UV module is a matrix of LEDs 10×10, the size of the printed circuit board is 100x100mm, the supply voltage is 12V. Modules can be arranged to increase the area of exposure. The recommended LEDs are UV 5mm 390-395nm. The best result is given by diodes 360nm but they are more expensive to stand. The optimal time for exposure of an unnamed negative photo-resist is about 100 seconds from a distance of ~ 200 mm.
The diodes showed sufficient reliability after 24 hours of continuous operation, they are all lit up, without any noticeable loss of brightness. The photoresist is exposed evenly, 100 seconds is the optimum time. But you need to keep in mind the result is 100% dependent on the purchased LEDs. A photomask can be printed on some inkjet film. The first exposure of the photoresist was successful:
A nice extra feature – checking the authenticity of documents by the UV marks.
CAD files: UVModule_FULL_05112017