Hmm, or maybe I'm just complaining because I had to do so many restarts
My solution: climb, bash right at the top, build. Coming back, mine off the corner so the other lemmings can get up. Let the climber rejoin the crowd and climb out once more, and build the crowd out (this one does need to be pixel-precise). The climber builds back to reach the top wall and bashes. I can't imagine there's any other way to do it.......
Anyway, I've solved up to and including 4.8 now, except for 3.15 still and 4.4 (Copyright Infringement Part Two) just because I foresee needing a lot of restarts for that one, so I've saving it for when I have a good chunk of time.
Nice levels, but the hints for 4.5 and 4.7 were silly! Both indicated particular tricks -- but not only were the levels perfectly easy to do without those tricks, I have no idea how to solve them with them! You must have very different solutions from mine.......
Oh, and this post makes me the board's #1 poster ;D ;D ;D