Is there any reason why I could not pour 1/2" diameter round blanks for use with slimline pen kits? It seems that using a 3/4" blank would be wasteful and a lot more work to get it down to the end shape.
I cast into 1/2" PVC tubes. Works well. I also cast with a 7mm pen tube in the PVC tube (centered). Then there is no drilling or gluing. Cut to rough length/sand to final length then turn. Don't know how to get any more streamlined.
Years ago, when the only available pen kits were slimlines, the standard pen blank was 5/8 " square.
So, as long as the blank is larger than your finished diameter, it is usable---IF YOU CAN DRILL STRAIGHT!!!