Use guttering for a trough to clean blind slats in?

I don't think you need to go to all that trouble. Take blinds down. Put them in the bathtub or take them outside and spray them with a hose. No need for a dedicated contraption.

Sounds interesting. I clean mine in the bathtub.

I did this last summer. but I used a long plastic snow sliding sled. that the grandchildren left here (we live in Maine) I put the sled on my deck floor, put some hot water with dawn dish soap &a little ammonia cleaner in it, wash them very gently (because the blinds are fragile) with a long handled soft brush.spread them open on the deck floor to wash, then spray them with the garden hose to rinse. hang over llawn chair to dry & rehang them inside. years ago I also used a plastic long trough that you could buy at the wallpaper store to wet prepasted wallpaper.

Thanks. After I posted this, I did see several ideas to clean the blinds.

Wow this is exactly the concept I was going for.... Thank you. You gave me something to work with

Here's a post that might help you https://chascrazycreations.com/dusting-hacks/