I now have the pictures that shows how the level was solved. It can takes hours just to beat it because I keep messing up.
1. When the level starts, build a stair wall that uses two builders to create a terrain that works like a free blocker, so the Lemmings won't get killed by the trap. Turn one Lemming on the right a builder, as soon as he turns around from the pillar.
2. After the builder on the right finish building and the crowd passes by, make one of the Lemmings on the left build stairs to the pillar and turn around and use two more.
3. Turn the Lemming that was building to the pillar a blocker, after he falls at the edge of the stairs.
4. Make one of the crowded Lemmings on the right a builder to close the gap, so they can reach the stairs above. Turn one Lemming into a blocker and as soon as one of them turns around, make him build over the pillar. Bash the stairs, so the crowded Lemmings won't get caught by the trap. Only two builders is needed to get over the trap on the pillar.
5. When the Lemming makes it over the trap and land on the pillar, make the crowd fix the stair, so they can all go home to the exit. Delay one Lemming with a builder.
6. Free the above blocker with a miner.
7. Make stairs on the edge of the left side of the one that was made earlier.
8. Send one Lemming to the exit by turning him into a builder on the destroyed stairs above, so he can turn around from it.
9. Dig through the stair and bash the one under the blocker to free him. Make the basher a builder to stop destroying the stairs immediately and turn around. Quickly turn the Lemming that was freed a digger and let him dig through the stairs until he makes a wall on the left that is big enough to make him turn around with a builder.
10. Turn the two last remaining around by making them build under the stair on the left side.
11. Do the same on the other broken stair.
12. That's the end of it.
