Pruning small trees

Growing trees from seeds have one upside (or downside, it depends) - genetic diversity. Having a number of plants with different genome, I'm trying to take advantage of it. Previously, I've started a 3 trunk fusion, which should make fast growing plants a bit larger. This time I'm going to make slow growing ones even smaller. 

Two smallest ficuses I put into a separate isolated environment, spent there 2 months and developed relatively impressive aerial roots and a multitude of small branches, but were not too interesting otherwise.

So I've decided to experiment with growing very tiny ficuses using these two specimen. 4 days ago I started with repotting:

I performed root pruning, trying to maintain somewhat radial root structure:

After repotting I defoliated them and performed radical pruning:

Four days later, I confirm they've survived and started to regrow some leaves:

Another two seedlings I've root pruned and cut 2 months ago and slip potted a week ago, have grown long but boring branches as well:

I'm not going to touch their roots this time, but I believe it's time for some pruning:

I've left one of two fork branches meaning to make trunk grow sideways. I'm cutting just above leaf nodes expecting cuts to die down to these nodes. I'm keeping couple leaves for these ones to make recovery faster, but eventually I want to keep their leaves small.
I've put cut branches to water with small amount of fertilizer and root hormone to see what happens to them:

Pruning follow up

Plants I've root pruned and trimmed 3 weeks ago not jus survived but grew several new branches and a lot of leaves. I consider experiment successful and other plants should be also ready for some training.

Speaking of other plants, they are growing unrestricted and look enjoying new space. The largest ficus is 18cm tall and at least 7mm thick near ground.

Smaller siblings in their new home also grew much faster than they did before, this is their progress for last two and half weeks:

This is the overall greenhouse view:

Summer is coming and on clear days temperature inside greenhouse can reach 50°C, so I've purchased a timer socked and set a schedule to turn off heating during sunny hours.

New greenhouse

Finally I've got a larger greenhouse so I can put every plant in a larger separate pot. The small nursery really was limiting their growth by now, so repotting was imperative. During repotting I was able to see some relatively large aerial roots:

There was a couple seedlings which have grown symmetrically sharing one cell:

I decided to practice in pruning on them. Anyway, they have tangled their roots so much that it was impossible to separate them without some damage. 

So went on and cut their roots to maintain kind of radial structure, but keeping some of roots at the same time:

Next day after root pruning, the first one (with fewer roots left) have withered a little. I believe that's because smaller root system can't maintain the same amount of leaves. So I've pruned their tops as well. After cutting stem ooze a little of nice white sap:

I've slip potted all the rest of the plants without much invasion, except for a couple of smaller ones, which have fallen behind their little brothers, like the one here. These I've just pulled out like carrots and put them into freed nursery cells. I should get rid of them completely if they don't catch up with others.

This is how greenhouse looks like now:

Larger volume requires more power to heat and more effort to keep humidity high, but after some experiments I've managed to achieve 98% RH and 24°C.