I've just made six batches of various CP soaps in Pringles cans (each batch filled two cans, about an inch from the top).
I lined them with freezer paper, rolled up then expanded to fit on the inside (waxy side to touch soap batter, if anyone doesn't know). I also traced the bottom on freezer paper, then cut it out and pushed it down to the bottom to cover the aluminum-coated bottom.
24 hours later, I cut off the bottoms off the cans with a knife, as close to the end as possible. That helped a lot in getting the loaves out. And they all did slide/shake out nicely with the freezer paper.
All the loaves came out nice and smooth, no problems.
I did try cutting the bottom off before filling, then making that the top and using the lid as the bottom, on the original can lip (with the lid lined with a freezer paper circle). It was okay I guess, but did leak some and just seemed to me not as sturdy and trustworthy as the solid can bottom.
So, my cans are one-use only. (I cut each loaf into 8 round soaps).
One thing I noticed, all of the soaps were made with either lard or vegetable shortening (along with coconut oil, and either olive or sunflower oil, plus various essential oils and assorted other things like pumpkin puree, apple juice, lemon rind, and clay). Anyway, two of the six batches cracked on top. I was able to just push them back down, then just sliced off a little of the ends after they were unmolded, so it was no biggie. I just thought it was interesting that the common denominator I found was that those two batches were made with the vegetable shortening rather than the lard. (The vegetable shortening does have all kinds of different stuff in it).