A person or thing that tacks things together, like with a small nail or pin.
A tacker is someone who makes things stay together. It's a helpful thing.
Examples:
The tacker put the papers together.
I need a tacker to fix my toy.
The tacker is in the box.
The tacker is so small, it's like a bug!
The tacker can put anything together, even a big house!
The tacker is my best friend because it fixes everything.