Where can I find more (Scissors Stickers)?

You can also go to where you got the object in the first place and obtain it for free. For example the scissors are in a cave in w1-1.

Whenever you get a new thing sticker, put it in the museum. The little plaques that appear under them will tell you where it was found (and this will help ensure you complete the collection).

You can buy the object again from the black market, it's all the way to the left. You can also pick the object up again where you first found it. From there, just make the thing sticker.

The best answer is that if you want to pay coins for it l, you can go to left side of the Sling-a-Thing in Decaburg, but you can also get it for free back where you first got it. In 1-1 go to the screen past where Kaymak crumpled the Comet Shard. In the back there should be a strange looking rock that you can hammer the middle of to enter a cave with the scissors. You will have to sling back at a Sling-a-Thing, but this way it is free.

If your wondering about specific Scissor type thing stickers, here's where you can find each one.

Scissors = Warm Fuzzy Plains (visible, just find it in the stage.)
Hair Shears = Damp Oasis (Secret Door)
Sewing scissors = Bowser's Snow Fort (visible, but NEED a Secret Door to access)
Tailor Shears (aka the Shears of the GODS!! OAO) = Shy Guy Jungle (Secret Door)

Get scissors at first from world 1-1. If you used it, buy it at the place to the left of the sling a thing station in Decalburg. :D