gg, this is pretty good for your first cube dominator level! as an expert, i can help a bit with your problems:
You can set the banners layer to the top during building! You should see it when you press the resize tab button in the top-right corner.
Chains go up infinitely. Even if you place one, the chain will go up forever.
The touch sensor is the background. You can use this to capture stunning scenes, or create an end scene.
Feedback:
Gameplay is really good, however it is lacking a bit in deco.
I would say the difficulty is around Hard/Harder.
Remember, this is all based on personal opinions. Feel free to criticize. With that aside, i hope this comment helps for your second level!