here's my attempt
I've tried to avoid textures at all, it seems to be hard to avoid repeatable pattern, also all these fractals aren't so fast to render, nicely to say. So, entire shape is created by ICE.
Render settings are almost default, except high quality for ray-marching ( but adaptive subdivision was disabled, set to zero), full light trace. About minute on AA 0-0, on Quad Core.
Here is simple ICE compound. Basically, it creates clouds in three steps. First step is a basic emission of just few points ( here's about 20).
Then compound emits a huge number of clones, distributing them in small tetrahedron between closest points - that's what you see in third pic. Last step is turbulence over all. Usage:
1: create empty point cloud
2: create no-simulated ICE tree
3: connect null or implicit cube ( implicit cube should be 1 unit size, for better preview). Scaling of null or cube, determines a 'bounding box' of cloud. Higher number of 'first points'
means more detailed base structure, turbulence is for small details. Compound is able to set particle color by relative particle position into tetrahedron, let's say, more transparent at border.
