Thought I’d share some pictures of my build. I went with a string of C7 incandescent bulbs. I was able to wrap the excess wire between the sockets around them which worked out pretty well. This was a test build so the string I used had 12" spacing between bulbs. I have some strings on order which match better in color (brown) and have 6" spacing which will make things easier. I used hot glue to hold the sockets in place. I cut off the sockets that weren’t needed and re-terminated the end of the string with an extension plug to accommodate additional letters.
That said, I will agree this design is a little wonky, and GF is sold out of veneer, so I had to use some from another source and bought larger sheets and cut them down, which hasn’t worked out so great. Of course no sooner had I done that, I finally found some 12x20 sheets with 3M backing on Amazon and so am awaiting those. It’s also a pain to do the veneer inside the letter cutouts and around the curve of the R. And what I used is unfinished and still needs stain. But not bad for a first attempt. I expect my next build will go a little more smoothly.
