Rubber Fig Banyan Bonsai using rooted cuttings as aerial roots. Ficus elastica

Ficus elastica banyan style. Fusing rooted cuttings onto branches of the tree to create "aerial roots".
I will include a link to the video in the comment for those who want to see the process.

Once these rooted cuttings (same cultivar) are fused with the branches of the tree, it will for the most part act just as true aerial roots do. Unlike aerial roots, they will try to back bud down below the canopy line. Those new buds will just need to be removed. I incorporated the top portion of these cuttings into the design of the tree so that it can produce foliage up top to prevent it from back budding lower. The nodes will become less noticeable over time.

I went back and forth between using this method and growing actual aerial roots. I chose to do this instead because this way I can place the "aerial roots" where I want them to be to create depth. Plus I won't have to damage/wound the branches to force roots growth.

Bonsai artists are well familiar with the fusion process to achieve a thicker trunk line and more impressive nebari in a short time. In nature, this process is called inosculation when pretty much the living tissue of trees simply grows into each other and over time fuse like a graft—could be branches, trunks, or roots.