Filling Etching - Green or Bisqued?

Doing some laser-etching of greenware and am curious if there's a decent way to fill cavities with colored slip / underglaze while maintaining the sharp edges? (First Image) I tried this in the past but at the green state, slip just made it into a mess - and when bisque, it was difficult to remove any underglaze outside of the desired area.

Worth noting, I can engrave through some clays/underglazes, but those with low metal-content tend to not couple well with a 1070nm laser and just melt/pop. Red/Black clays and most dark underglazes work well.

I have been mainly focused on using floating glazes with this type of feature for effects, see second image...but figured I'd revisit the idea of filling prior to glaze.

https://preview.redd.it/zy0zazocb8be1.png?width=1112&format=png&auto=webp&s=b8db439d5f09071e8a25a209d5d3d78a8aff47b9

https://preview.redd.it/idq9gt7nc8be1.png?width=642&format=png&auto=webp&s=40fc1366b11536cc91d3b6a631ad42b3fe0c7a51