I don't know why, but at some point I was kind of obsessed with creating a system for essentially collecting everyone's trash so it can be used by other people. One minecrafter's trash is another minecrafter's treasure? The recycling center is a very extreme version of this. Basically, I would add a recycling chute to everyone's house, the chute would go into a series of underground tunnels which transports the items to the recycling center.
Unfortunately this system is now dormant as the majority of players who I've connected this to either don't play anymore or just don't need it.
First, the player throws crap they don't need into the recycling chute, These chutes are located all around town and in player houses.
Then the items get dropped down into pipes which move the items to the recycling center. There is an overcomplicated system for detecting if the item actually made it through the pipes. The pipes are near Y level 0 to stay out of the way of other builds. We built it before the cave update which lowered the minimum Y level.
Then other players stop by the recycling center to see if there is anything they want. Because of the nature of the items players are disposing of, most of the time, the recycling center was just used to get basic buildings blocks for large scale projects and terraforming. I also bring new players by the recycling center for them to grab some free items as a little kickstart on my server.
When the items go into a pipe, they go over a pressure plate which activates a toggle switch. When the items get to the end of the pipe, they deactivate the toggle switch. I can connect the switch to a visual warning.
This is another build that was done before we added Create Mod to the server. I feel because of how Create effects basic resources and storage systems, players are more interested in having their own storage systems, even for the plethora of crap they obtain over time. Because of this, I feel that providing more factories which produce resources for free is a better option. Players often ask each other for stuff and help, so this type of recycling system isn't really needed anymore.