Sometimes a bit of poop does stick to the slide, but a poke with a stick is all it takes to have it roll down into the bin. Now, we do live in a dry climate, and chicken poo tends to dry out pretty quickly. Don't know if this is the same everywhere. When we did the annual, rake out all the bedding and wash out the coop, I took the poop slide and hosed it down and any remaining spots came clean really easily. Since the poop slide is more or less propped against the wall under the roosts, removing it was pretty easy.
The corrigated plastic I used is the kind of stuff folks use for political yard signs or some store signs, you know the kind that are on little metal legs out in the medians or road right-of ways. Mine came in a big box...I think I used two for the poop slide. I also used a big 4'X8' corrigated plastic political sign for bottom of my coop, covering the plywood floor to make it easy to clean. As to where to get that material, you could probably get it from a sign store...it is an election year, so you could poke your head into your county Republican or Democratic headquarters and see which local candidate is using that kind of sign in their campaign and see if you can take a few for your yard (hopefully this is a candidate you like, so you can actually display the sign before your let your chickens poop on it) or you could do what I did, which is actually run for office and then when you lose, let your chickens poop on your political aspirations.
Originally I had about 8" between the roosts and the slide. Later, when my little pullets became big heavy-breed hens I worried that the roosts were too high. They were coming down from the top roost with a loud THUMP every morning and I worried about them hurting themselves, so I removed the bottom section of the roost ladder and moved everything down about 16". At that time I also gave the girls a few more inches of tail room. The photo shows the original setup: slightly steeper poop slide and less tail room.
