Here are photos of what she constructed (on her own, not following a manual) the very first day she played with her K'Nex TinkerToy set and her descriptions of the creations.
"A boat...the green part is used to give shade to the boat and makes bugs not go into it."
"I built a church!"
"I made someone's mouth and eyes and his cheeks...that really looks like a mask."
"I made a hammer! Even though there's only two things in it, it still looks amazing? A pen and a hammer! The blue part is the cap of the pen."
"An alligator's mouth! And the teeth."
"It's a ladybug!"
"Look I made a spider...the spider is sneaky."
"That's an X for pirate treasure."
(The bottom and top parts actually spin when you give them a nudge with your hand.)
"A music box!"
It looks like fun...and it was completely from her imagination for this set, without any assistance...but the creations will become more complex and older kids enjoy these sets too. I picked up the manual and followed the diagrams to create this...a man in a car (the wheels actually spin on the rods...so the vehicle moves on the floor when you push it...and kids can play with it).
UPDATE (6/21/14): Lina has now discovered the joy of the TinkerToy Building Manual. Here are a couple of Lina's new creations: