[hinterlands]

There are gel-like resins, but you'd have massive issues with air entrapment. There's really no shortcut for making these. Casting in layers is the most common approach, but as noted in the article, it's hard to avoid slight refractive index discontinuities.

[Chris2048]

Strange thought, but, if you shine a uv laser through uv-setting epoxy, does it create a fishing-line-like column of set resin?