Artists: What are different mediums to paint on?

Rocks, pebbles, shells. Slices of a log, You can incorporate the natural contours of the object into the painting. Wood will have to be primed first. Acrylic paint will work on the rocks and shells.

Fresco; wet plaster.

I have a really nice still life done on the top of a wooden cigar box.

Mirrors/panes of glass/picture frames
Cardboard
Old paintings you find at thrift stores
Shipping pallets. They’re often given away for free on Craigslist.
Reclaimed wood – that is, instead of throwing away that nasty old dresser, take a hammer to it and paint on any flat pieces that fall off. (I have a couple of homemade board games painted on drawer bottoms)
Mason jars/teapots/teacups/saucers/coffee mugs
Sheets of tinfoil
Glass Coke bottles.
old curtains

ME! Paint on me, please!
Ooooooorrr, using tied down, I mean @downtide‘s suggestion of wood and primer, use the primer in certain places, and none in some places to get added effects.

Oh my gosh. The possibilities are endless.

the floor
street
rocks
pebbles
shreds of paper
a brick wall
obviously, canvas
a box a scarves (it’s pretty awesome)
old picture frames
antique furniture frames
shoe strings
broken light bulbs
a light bulb
shards of broken glass
a box itself
torn cardboard
ripped newspaper
shit, go Andy Warhol and paint on some garbage
ask a few friends or neighbors if you can paint on them (really fun)
yourself
old wax from used candles
some rotten fruit
old carpet
a gathering of wood

I could go on for hours.

The thrift store is your friend.

Do you mean different mediums to pain with, or different surfaces you can use as a canvas?

billboards
barn walls (or house walls, for that matter)
gravestones (why aren’t they decorated better? I wonder)
sailors’ ditty bags and chests
luggage
shirts, belts, clothing in general

Human skin

Cave walls

If you are asking where or on what can you paint on, let’s put it this way, you can paint on anything that is dry, non-chalky, not oily, doesn’t sweat, you can even paint on surfaces that are impenetrable it just won’t be permanent; same with skin and fur.

My friend has some leftover pieces of stainless steel sheeting that I’m going to try to paint landscapes on. Not sure how well the paint will adhere to it, but I’m going to give it a go.