So I bought a cheap acoustic guitar ($15) from Goodwill and thought it would be interesting project to turn it into a cheap resonator guitar. After checking online and seeing what others had done, I did pretty much the same with a few adjustments to the process. The process was a bit sloppy, but in the end it came out alright!
The first picture is the finished resonator, the second is what I started with (I forgot to take a picture of the ACTUAL guitar I used before cutting it up!). The soundhole covers are drainhole covers, the coverplate is made out of an old metal dish tray, and the bridge covers are two drawer handles. I wimped out on fashioning my own resonator cone/biscuit bridge and tailpiece, and just bought them cheaply online. I also bought a cheap piezo pickup so that the resonator could be amplified.
This is by no means an all inclusive guide to the process I took, more of a rough idea. I kinda just ran with the concept and paid scant attention to precise details...
Step 1: Cutting a Hole in Soundboard, Making the Soundwell
The first step was to cut a hole in the soundboard so that the soundwell could be inserted. The soundwell is a wooden bowl, about 3/4" thick, that I bought from Target. I wasn't particularly exacting in this process, but I cut the bowl so that it would fit snugly in the newly made hole. Rather than removing the back of the guitar in order to fit the soundwell, I cut it in half so I could jimmy it in there.
I cut a few arches in the bottom of the "soundwell" so that some noise could escape into the rest of the guitar body. After fitting it in, I applied a heavy dose of wood glue to hold it in place
Step 2: Wood Puttying and Sanding Smooth
After the glue for the soundwell had sufficiently dried, I sanded off the tacky blue paint so that the guitar would be smooth and ready for a new stain down the line. I also applied a heavy dose of wood putty to cover the seams between the two pieces of the soundwell, and the gaps between the soundwell and the guitar body. For the sanding I used various grits of sandpaper and a trusty wood rasp.
Additionally, at this point I cut a new design in the headstock since I didn't like the original shape.
Step 3: A New Cover for the Old Soundhole, Test Placement of Pieces
I cut a new piece to cover the old soundhole. The shape of the piece was only a temporary design, and as the project progressed I adjusted it to account for the placement of the cover plate. The wood I used ended up being too thick, so I had to sand it down later.
In order to make sure this wasn't a complete waste of time, I put the resonator cone in and strung it up for a test play. It sounded good, but it was necessary to adjust the string height.
Step 4: Cutting New Soundholes and Coverplate
I used a dremel to cut the new soundholes on either side of the base of the neck, having already determined the hole size with the test placement of the drainhole covers.
I used an old metal dish tray (another Goodwill purchase for $2) to cut the new coverplate. In order to get the correct size, I used a piece of cardboard to cut a circle until it covered the hole in the soundboard appropriately, and then traced the circle onto the dish tray. To cut the dish tray, I used cutoff wheels on the dremel tool, and then sanded smooth the cut so that there were no burrs.
I also cut a rectangular hole in the coverplate to account for the bridge. Using a drill, I cut several holes of different sizes in the coverplate.
Step 5: Installing Pickup and Staining
The piezo pickup I bought cost around $15, and it was pretty easy to install. In hindsight, I should have accounted for the pickup before gluing in the soundwell...it took some maneuvering but I was able to get the pickup input under the soundwell and into the hole I drilled in the side using a piece of dental floss attached the input.
For the stain, I wanted to get a dirty look, so I used a few coats of different color stains. After finishing the staining and applying a coat of polyurethane, I superglued the pickup to the underside of the resonator cone. It ended up dampening the tone quite a bit, but it was nice to be able to plug it into an amp.
Step 6: Applying Soundhole Covers and Coverplate
In order to secure the drainhole covers over the new soundholes, I glued two wooden blocks to the back of the guitar so that the drainhole covers cover be attached by a woodscrew to the blocks. I spray painted the inside black.
I attached the bridge covers (two drawer handles) after drilling holes to screw them onto the coverplate. I screwed the coverplate to the guitar body after drilling small holes around the circumference, and then I glued on the piece I made earlier to cover what was left of the old soundhole.
Step 7: Finished!
For a more abbreviated rundown of this process, check out a youtube video I made: