We've just finished renovating our main bathroom, and needed a vanity light. We didn't think our requirements were particularly stringent - we just wanted it to use LED bulbs, to have a fairly contemporary vibe, and be bright enough to illuminate the whole room. Well, it turns out that we'd have to pay top dollar to get anything like what we wanted (e.g. this one), so I thought I'd build something instead. The cool thing about making something simple is that it looks minimalist, which is a style I like. Total cost was ~$50, the vast majority of which was for getting the glass cut.
Step 1: Design
I had the previous light fitting from the bathroom - it was a simple strip of 6 light bulb sockets. It was wired in two halves and it occurred to me that if I cut it in half, I would have two 3-light fixtures. If I concealed it behind a piece of frosted glass mounted in some wooden supports jutting out of the wall, I would have a nice contemporary light fitting. I played around with Sketchup until I got something I liked (.skp file attached at end of this step) that would also be easy to make and mount. All it needed was a couple of offcuts of construction lumber and a few small pieces of plywood, in addition to the fitting I had. I would have to get some glass cut to fit, but this was no big deal.
[if you want to make something similar and don't have an old light fitting, buy light bulb sockets with mounting brackets. The advantage with this approach is that you can space them as widely as you like, add or subtract bulbs, whatever you like. You will likely need some additional wire and wire nuts - if you're handy enough that you're attempting this project, you will probably have some lying around]
Caution: electricity is potentially dangerous. If you are in any doubt about a task involving wiring, consult a professional electrician.
To make the wooden frame, I used a tablesaw (any saw would do) and a cordless drill. I used my router table to carve the notch that holds the glass. I also used drywall screws and wood glue to hold the whole thing together, and a drywall anchor and a deck screw to fix the fitting to the wall.
I bought a piece of frosted tempered glass 6 mm thick (1/4") with polished edges. Mine was 520 × 230 mm. Your local glass shop will do this job; mine cost $44.
Step 2: Make Brackets
I cut two square pieces of wood 190 × 190 × 38 mm out of a piece of 2 × 10 construction lumber I had lying around. I selected the squares carefully, avoiding cracks or warping. I retained some knots because I liked them and they were sound.
Step 3: Cut Grooves for Glass
I cut a triangular piece of wood at the same angle as the glass needed to be set in the frame (24 degrees), and taped this to the workpiece when routing the groove that holds the glass. See pictures for details. I laid this out carefully, as it was easy to screw up the angle, the position, the depth and the length of the stopped dado. The groove should be wide enough that the glass slides easily within it (about 6 mm or 1/4"), and 17 mm deep. Luckily, one of my few router bits was a 1/4" straight bit, which just accommodated the glass. I made three passes to reach the requisite depth. In hindsight, I would have made the groove just a little wider - it was a tighter fit than I would have liked.
Step 4: Plywood Box
I cut five pieces of 5/8" (15 mm) plywood into the following sizes: 460 × 68, 460 × 65 (2), 98 × 65 (2) mm. I then assembled them into an shallow open box, using wood glue and drywall screws. I painted the box white for maximum reflectivity. But not the ends, because I was going to glue those, and not the back, because that was going against the wall.
Step 5: Halve Sacrificial Light
I cut my old light fitting half with a hacksaw. All the wiring and sockets were in place for me already and the fitting dropped perfectly into the plywood box. This of course was more than a coincidence, because I'd designed the new fitting around the bones of the old one.
I also trimmed the white face plate down to fit in the box, too. I didn't think I'd have to initially, but the satin frosting wasn't as opaque as I'd expected and I didn't want to see the wiring through it when the light was off. Any metal plate would work fine in this context.
Step 6: Assemble
I glued and screwed the ends of the plywood box into the top back corners of the square brackets. I left a small (~2 mm) gap between the edge of the brackets and the box so that the brackets were pulled hard against the wall when it was fixed in place. I drilled holes for the wires and for the mounting screws.
Note that I needed to take into account the necessity for the light fitting to cover the hole in the wall. I used a piece of white-painted wood with a triangular cross-section underneath the plywood box. It doesn't show up in the plan or the pictures because I added it afterwards, once I knew exactly how big it needed to be.
I stained the brackets and went over the whole thing with several coats of clear finish. It is going to be in a bathroom, after all.
Step 7: Mount Fixture
I screwed the fitting to the wall using a deck screw (where there was a stud) and a drywall anchors (where there wasn't). I wired up the fitting, added LED light bulbs, slotted the glass in place, and that was it. Gif above not really representative of what it looks like when you switch it on, I was just messing around with the slow mo function on my phone and that is the camera optics adopting to the sudden surge of light. It's not easy to photograph a light source and have it appear like it does in real life.