I'm running out of accolades for your work, Malcolm! Those are fabulous!
I use Zar oil-base poly and I purchase 6 oz. plastic bottles from Midwest Bottle Company. I buy the caps for the bottles from them. I fill the bottle with about 1/4 semi-gloss and 1/4 gloss. Then finish filling the bottle with odorless mineral spirits that is labeled "cleans up paint" so it is stronger than some of the other mineral spirits. Then I put the cap on and shake the bottle to mix the ingredients. I generally fill 6-at a time.
To apply the finish I use the blue paper shop towels. I cut them into 1/4s. To apply the finish I fold the towel to 1/4s again making it about 2" square by 4-layers thick. I don't get runs and just throw away the towel so there is no cleanup.
Sanding...I generally sand the wood with an orbital sander using 100, 120, 180 grit paper. After I apply 4 or 5 coats I have a 5" orbitals sander that I set on half speed. I attach 600 grit black wet and dry sand paper. I use a 1" foam brush to apply the same mixture to the sandpaper and to the box. I sand for 30 seconds or so per side of the box wiping off the mixture when I finish with that side of the box. After 8-hours I start back applying the finish. After 8-hours or so I will apply more until the finish looks right.
Hope that helps. I have used Zar for 25 years or so and have used this same method on kitchen cabinets, tables, a couple coffins, funeral urns and a host of other things.
Malcolm / Kentucky USA