I removed a well built permanent alley that was just to small for what we needed.

I have set up an adjustable alleyway, tub, and and hydraulic chute.  It is all freestanding bolted or pinned together.  It is fed by some of the old coral system for now but isn't the best.  I would like to piece together more wide alleyway to feed the tub and some gates.  It would be nice to continue with everything above ground in case I need to move or change something to get it right.  I don't want it to be too light weight and flimsy just don't want to put permanent posts in the ground just yet.  Who makes something like this?  Individual pieces that have cross bars on the ground and overhead to make it fit the layout I want.  I may have to build some pieces myself but wanted to see what I could buy to speed up the process.