These look great. I love the color and I bet the look even better in person. I would like ask a few questions. I have not ever done any woodwork but have access to a wood shop. Why did you paint the inside before putting them together? Which joints did you put filler in? Would you do anything different? Did you somehow make the bottom of the speaker come apart easily to pull out the crossover?
No problem- all good questions.
I painted the insides first because I didn't think I could get my spray gun in the tight corners of the rear of the speaker, and if I did, the paint would be uneven. Paint spray guns really need to be 'swept' across a surface maintaining the exact same distance from the work piece and a very uniform speed. I was worried I couldn't do that if I waited to paint the inside of the speakers until they were assembled. Now that I'm done, I would have probably gotten away with it since most of the inside is covered with no-rez anyway.
After the first primer coat following assembly, I sanded that coat then added a very light 'skim coat' of filler where the front baffle edges meet the edge of each wing- this created a seam vertically from the bottom to the top of the speaker on each side. Also, where the inner braces meet the rear edges of each wing. Very minimal amount is needed because the flat packs fit so nicely together. You could get away with not doing this- but if you have so much time into these already, why not spend an extra 10 mins per speaker was my thinking.
I left the bottom of the speaker unglued until the very last step- after the drivers and crossovers were wired up and connected. Since I had 'dry fit' the base during glue up (to make sure everything was in alignment during glue-up) they fit perfectly at the end of the project.
Things I'd do differently:
1- Order more wire from the start (I actually placed TWO addition orders for the solid core wire to wire the highs and mids)
2- Order more solder- I used three times as much as supplied (I probably over soldered, oh well)
3- Take some scrap MDF, glue a few pieces together, prime, prime, finish, finish just like you're planning to do to your speakers. You need to develop your process first before you get your flat packs (I actually did this, but I wanted to share how valuable it was for me)
4- If using the same primer as I used- don't thin it. I thinned it the first time (my spray gun was struggling) with paint thinner and it worked, but took forever to dry. THEN I read the label and found out this primer cannot be thinned

Other than those few things, not much I'd change. Keep in mind this is not a few-beer project. Have patience, take your time, may require several cases of beer over many weeks.