How can I upcycle an old slatted door?

Cut in half and use for two sides as a shelf for plants, porch or books, just add boards for the shelving then paint or stain.

Here is one idea https://www.hometalk.com/diy/build/shelves/bi-fold-doors-turned-corner-shelf-21340411

Bi-fold Doors Turned Corner Shelf

I have a lot of doors like that and hung the right way on the wall it would make a nice place to hang pictures (metal hooks for slats are sold at hardware stores. . . I think they are really for hanging pics from crown molding)

A friend of mine used her to hang her jewelry. Here it is: https://www.hometalk.com/diy/bedroom/organizing/jewelry-center-from-re-purposed-shutter-34539943

Jewelry or Utensil Center From Re-purposed Shutter

Plant stand.

I found 2 sets by the curb that were broken and down right nasty. I took them home and repaired them. Then I separated the two sets. (4 single individual doors). I painted them all a terracotta color. I got 4 1/2 tall letter stencils. One one I painted "WELCOME" going down wards. Then another door I painted my address. Starting at the top going all the way down. I have a long address name. Lol. I added some pretty design on the top and middle were the knob use to be. I also put a clear coat over the painted surface to protect the paint. I hung them on the front metal columns that stand in front of my home. Made it look really nice from the street. Its just an idea......