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
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