Is there a trick to scribing Tamiya putty?

Gentle, slow, repeated passes until you get the line you wish.

Hi,

I'm not real familiar with Tamya Putty, but for stuff that can be a bit brittle when dry (like Squadron Putty) I have tried coating the area with either sanding sealer or airplane dope, and letting that dry, prior to trying to do any sanding, or scribing.

Pat

Super sharpness!  I use my scalpel for this (and for canopy masking( rather than X-acto knife).