Working on a Christmas gift. I got the wood scrap, but I think it’s walnut. Eventually planning to polyurethane and fill in the engraving with black paint, but I’m stuck on how/weather to stain it.
I have a few stains from various projects, but on a sample piece they showed up really dark, and didn’t show the texture that well. It’s a little too late to do boiled linseed oil.
What would you recommend?
The wood looks nice to me as is, I would just do oil. I probably wouldn't use polyurethane unless it needed water protection / durability.
Well my concern is filling in the engraving. I wanted to coat it in something waterproof so I could apply paint and just wipe off the excess. Is there a better way to do that? (Also there's more engraving to be done to the sides)
For getting paint down into an engraving, a simple method is just to get it in there real good regardless of technique, then use a power sander or sanding block to go over the top surface and remove any paint. THEN do your finishing steps. For walnut, Danish Oil is the lazy man's cheat-code.
I was thinking that, but won’t the oil mess with the paint?
Nah, once cured the paint will be quite solvent resistant.
I had a similar project that puzzled me. I took a blow torch to that fucker to bring out the grain then gave it a generous coat of amber shellac. It's now my favorite Magic card box.
Picture? That sounds like a neat effect.
Just got back from the wood shop. Guy there suggested dying epoxy, filling the engraving, then sanding the epoxy flat before applying oil.
Just realizing now that that will eliminate the 3D nature of the engraving, but given my time crunch, it might be the best plan.
Edit: just did a trial run with some random acrylic paint and BLO. Really thought the oil would affect the paint, but apparently that’s not the case.
This scrap was roughly sanded with 120 grit for just a few minutes. I expect it’ll look great with proper preparation. 
Not a woodworker but could you oil it, pour clear epoxy, sand flat and re-oil? That'll keep the 3d effect to some degree.
How do you mean? My assumption is that the epoxy will completely fill the engraving. And because it’s opaque, it’ll look like a flat layer on the outside.
Ah, thought it was clear epoxy.
This was exactly my thought
Ended up painting with generic hobby paint, sanding down, and finishing with BLO.
I was afraid the BLO would interfere with the paint, but it had no effect.