So I ended up having a spare weekend to finish off this project, and I'm pretty happy with the results.
Timber putty filler was used to clean up any of the edges, and I ended up choosing an interior stain (Merbau) for the marine plywood. Tested on some offcuts before applying (thanks for the tip @Johnnynl), which allowed me to see how much I should be applying.
I had purchased a leather pull from ebay since my last post, and added it onto the front, along with some gold hinges on the back.
A few learnings around the core frame and getting it 100% right would have saved some time with the outer timber shell, but otherwise overall pretty satisfied with the end result!
Finished vinyl record boxGold hinges on the backLeather pull purchased from ebay
Great work! That stain looks spot on, fantastic choice! Where did you come up with the leather strap for opening it, haven't seen much like that before, I'm a huge fan of it. I'm going to pinch that idea for a project of mine if you don't mind. Whatever filler use used turned out invisible too, I had to look back on earlier images to see where the holes were. Ace work!