Heres the ice farm machine that I'm planning on making. It freezes pretty quick, about 5 minutes for most of it to freeze and perhaps 10 for the rest of the way. Even though the tutorial says to use snow, it turns out that wood works just as well against pickaxes with efficiency since that's what people are most likely to use.
I'm planning on maybe spruce wood for the flooring, not sure what I want to use on top of the pistons though. Since it freezes pretty quickly, you can use one while you wait for a second one to freeze.