Resonator Outfitters (Paul Beard's parts division) has a set of plans for a round neck metal body biscuit. It should be fairly easy to modify these to work with wood.
http://www.resophonicoutfitters.com/product/RNB-2.html
Some things to think about with a resonator - first, most of them have some sort of neck stick altho I have built a tricone with a conventional bolt on neck. (I've also tried to repair a cheap PacRim reso with a dovetail that was a complete disaster). You usually use the neck stick and some little "mushrooms" to adjust the neck angle which is how you set the action (you have a limited amount of adjustment at the saddle). The fretboard extension is traditionally screwed to braces in the upper bout, the screws are hidden under fretboard marker dots. Here is a picture of a metal biscuit showing the neck stick and sound well.
It would not be hard to duplicate that in wood.
Second thing about building a reso is that the location of the bridge becomes locked in stone early in the build (when you route the soundhole). You need to carefully decide scale length, whether you want any compensation, action and neck angle at that point - its not like an acoustic where you put the bridge on last. Think about your bracing under the neck and if you are going to have a truss rod how it will adjust (I made a slot head and put the adjuster in the body - its a hassle but it does work). I would suggest getting all your hardware before you start and carefully working out the plan view of the neck, cone, cover plate and tailpiece. People say that the cone compresses under string tension, that has not been my experience (at least its pretty negligable)
Anyway, here are a couple of pictures of my tricone woodie
Top and back are approximately 0.125, top is flat, back is domed. Body is a bit deeper than traditional which is a trend with spiders - don't really remember why I did it here. Cone well is birch plywood - I did a couple of mockups to figure it out - a round well would be much easier. Wood is koa - makes a really nice combination - play it gently and its almost acoustic sounding, dig in hard and it barks.
Let me know if I can help.
