I posted earlier that plaster of paris is used as a filler, mixed in with your oil recipe.Also many makers have used spar varnish as a filler but always sand back to bare wood after application, before next coat.
Polish, melt your carnuaba wax and dilute with white spirit until it has the consistency of butter when cold. Remember an application of wax will prevent penetration of further coats of oil.
To polish or buff up for a finish you should use a rubbing block wrapped in lint free cloth (old tee shirt cotton)if you just use oil on your fingers you will be rubbing until you wear down to the elbows.