Thank you very much for the compliment! I finished up one of the 20mms yesterday - it came out quite nicely, though perhaps a little bit oversized. I was able to make one decent gun shield out of sheet styrene - it doesn't look half bad! The platform aft for the .50s is almost done and I may get it in place today - pics and narrative to accompany it, of course.
Thanks also for the offer on the PE - but part of the real fun on this project has turned out to be doing what I can with what I have on the table. My inspiration there is a approximately 1/72nd 4 stacker my grandfather built from Popular Mechanics plans in the early 30s - nothing but very common hand tools, sandpaper, metal shears, and every last bit of material found around his home. My Dad still has that beast sitting downstairs, hopefully I'll get some pics of it one of these days.