How do you do a few things with furniture?

[MOZZYSTAR]

I've seen imitation windows/fools portals (I think) partitions (I think again...), and them taking the place of real windows (it seems). How does one actually get that to work?

Another thing I've seen is floating tier 4 fish tanks (that look to be attached to the ceiling somehow). How does one do this?

Thanks ahead of time!

[Dustytome]

How does one do this?

Here's one of the more recent how-to posts.

[MOZZYSTAR]

Here's one of the more recent how-to posts.

Oooh, thank you!