In this instructable I hope to show you how to create a custom replacement bathroom fan cover from some spare plywood and lasers. I guess you could use a router, but that's way less cool.

I removed the fan cover in our bathroom long ago in order to vacuum it out. But once I had it down I was never able to get it back up again. Turns out the bottom of the fan is 3/4-1" above the face of the ceiling, meaning that the spring clips could only grab the tabs inside the fan housing with maybe an 1/8" gap to spare. My fingers wouldn't fit and I'm not talented enough to find a way to get it done with pliers or something.

So the hole in the ceiling stayed for a while... then came the laser cutter!

Step 1: Patch and Repair Cutout

Even before the original fan cover came down the ceiling was never really in good shape. But at least when it was up it hid the ugly hole.

To repair the ceiling, I had to cut off a bit of extra material to finish squaring out the hole. I then just went to work with a typical gypsum repair job with drywall compound. Let dry, sand and paint to match adjacent ceiling.

Step 2: Choose Design, Material and Prepare File for Laser Cutting

My wife and I have a thing for nautical sea monsters, so we figured we'd extend this to the bathroom with a cephalopod. So we started looking for images we liked and found a great simple image of Cthulhu.

Due to the fact that we found a simple image, converting it into a cut file for the laser cutter was very easy. Using the trace tool in Corel Draw, I converted the raster image into a vector based image. In order to maintain enough material between cut-outs, and keep it's strength, a little adjustment was necessary.

Using the 'Contour' tool, I was able to offset the cut line just inside the original shapes, and remove the larger boundary cut line. This makes the space between the cuts larger. Be sure to use the same settings for each shape so no asymmetry develops. Once I was happy with the cut-lines I created a dashed round border to finish of the look.

While I considered using acrylic to make the fan cover, I went with 1/4" birch plywood instead. It's cheaper and since it won't be in contact with water, I figured a good coat of paint would keep it protected from the humidity in the bathroom.

Step 3: Paint and Attach Screen

Depending on the quality of the cuts from the laser, a small amount of sanding may be required to smooth the edges and remove any splinters or burrs. I lucked out and had no spots which required any work.

Before painting, make sure that the surface is free of any dust and oil. Any colour and sheen can be chosen, though I went with flat white to match the ceiling. Though the surface could be painted with either brush or sponge, I opted for interior/exterior spray paint because I didn't have any flat ceiling paint at home. I was quite happy with this in the end, because it left a very professional look and surface quality, with no brush strokes to worry about. If you're not experienced with spray paint, I recommend more thin coats, rather than fewer heavy coats, minimizing the possibility of paint drips.

Once the paint is dry, the screen can be applied. While not strictly necessary, I added the screen to be used primarily as a blackout shade, so you can't see through into the fan housing. If your cut pattern has holes small enough so that you can't see behind it easily, you can forgo adding the screen. NOTE: If you add a screen, more frequent dusting/vacuuming will be required.

I chose to use a black/charcoal coloured fiberglass screen, as it's cheaper and easier to work with than metal screens. Cut a piece large enough to fit over the entire under side of the cover. With a silver sharpie mark the perimeter of the pattern on the screen, leaving enough room for fasteners/glue. Cut to size.

Hold the screen over the cover and make sure it fits, without pushing over the edge. Once you have the screen in a good location you're ready to attach it. Being that I was using 1/4" plywood, mechanical fasteners were out of the question. Which I found out after stapling both the screen to the cover, and the cover to the floor. OOPS! So instead I grabbed some spare caulking I had lying around. I put a few dots down where there was room and spread it with my finger over the mesh, careful not to push any into the design. I just used a paintable interior acrylic caulk, it doesn't have a whole lot of holding power but it doesn't need it because the screen ends up sandwiched between the cover and the ceiling anyway.

Once I had one screen cut out and attached, I held it up the the fan to see what it would look like. Turned out that it was still too easy to see through the screen into the fan housing. So to fix this problem I simply added another layer of screen, laid out at a 45 deg. angle to the first layer.

Step 4: Mount

Here's the easiest step: mount. I had added mounting holes to my cut file, but if you forgot you can just drill them by hand. I secured the cover to the ceiling using 1" long wood screws, just make sure you choose screws with a colour and head type that will look good.