Last year after the season closed I got a used custom z-axis for a song, but never got the chance to fish it until this season. Casts like a dream, but after several all day outings I'm realizing the grip is a too fat for my hand and tires it out by the end of the day.

It's not that far off of some grips that I fish all day with no problems, so I was thinking I could modify it myself. I checked out the rod building section in here, but that's for shaping off the rod. Anybody got a good method for shaping the handle once it's already on the rod? I'd prefer too not invest a lot of money in tools, but don't mind investing quite a bit of manual work time. Any help is much appreciated!