Factory trap's chimney looks like wall

[SimonN]

Lix 0.10.0

Icho and I played Merge Sort, the singleplayer level by geoo in lemforum/Daunting. Icho wasn't sure whether the chimney of the factory trap was solid. If it were solid, we'd have to reserve a miner for it. But it's air, because it's part of the trap.

Expected instead: The chimney shouldn't look like a wall from the construction tileset. It should clearly be hollow.

Ideas:

• Make the chimney come diagonally out of the factory above the ground, but keep it straight upwards at the top, as it is now.
• Make it darker, blend it with the factory's body, reshape it, ...