I used a drop-saw to create these slots:
Due to the circular blade, it's obviously left a bit of the wood in place, more easily seen here:
My question is how can I clean up these slots? I've considered filing, of course, and I'd be happy to buy a file that fits if that's the best option. But there's a lot of wood there and I think filing would take a long time.
I also thought of chiseling. Again, I don't have a chisel that fits, but am happy to purchase. However, I can't see how it would actually work. Sure, I could chisel the sides of the slot, but then how would I actually knock the bit of wood out? I'd need a tiny chisel to fit the slot - 5mm or less.
Are there other options?