How do you get to the [spoiler]

I can't get to the
It's driving me crazy.

Notice: The castle i will talk about is only accessible to people with at least 24 coins.

The blue button in the castle near the Warp Zone has learned you how to make stuff, right? That includes keys. Go to the dead end in area 4 and use that key there. Using this new ability, you need to advance until you see a big tower. Do not enter it, the is behind those boxes.

Oh ok, thanks. Now I need to get the coins

Maybe Firecat's map helps?

Spoiler: (click to show/hide)

That crayon level was quite challenging actually!

To get to it or to beat it?

If it's the second one, try beating it under these conditions.

Firecat's map is kind of confusing. I'm still working on getting the coins, but I've almost got it.