Of course, at every conceivable opportunity I try out my ideas, try the fitting of pieces to cut down on the opportunities for a nasty surprise. What works on paper never exactly pans out when you get to cutting. For instance, cutting any kind of frame with 45deg corners is tricky business, even with a miter guide (bought special for the occasion, I might add.) Also, in an attempt to get the frame just a little shorter because it had too much wiggle, I cut just a hair too much off and had to trim the long pieces. This made the long pieces too short and to fit the window, so I had to dremel the edge with a sanding attachment until I got it to fit. So yeah, trying to out with dry runs are important.
Got to gluing. Remember to take caution when screwing through lath, it's weak stuff and prone to crack and if you don't have your driver set to the lowest torque setting you're going to strip the hole. To clamp all the pieces in place I used wood screws (with pilot holes) to keep everything locked tight while the glue set. It also helped to hold in one side while precisely placing the others. When I was ready to glue I'd unscrew one side, spread the glue in, screw it back in pace and then unscrew the next section. I left the top unglued to fit in the plexiglass as findal step.