MASTER-88 - I tried your level ideas in Lemmix:
1 - I did this one without using the climber, bomber or digger. This might only be possible due to a version difference (does the SNES version require 2 builders to get across that gap?).
2 - I like this idea. Timing bombers is bothersome though (that could be a good thing, I don't know). All skills used, but I think the time limit is somewhat generous.
3 - Took me a while to figure out how to use the miners here. All skills used. This solution was similar to the way I normally do this level anyway.
Good ideas on the whole, but not too difficult. This may not be the case on SNES though.
Keep 'em coming if you like. I'll play them