Palm blanks that I have no experience with.
You are on your own here. I cut the blocks down to appx 3/4" x 5". Click the images for closeups.
$27 mailed in the conus
Drill the blanks for your pen then soak in wood hardener. Then turn down the blank with light cuts and sharp tools. Leave a little proud of the bushings and sand to final dimensions. Those crosscut blanks will be interesting but delicate.