So this mega block will take up 4x4 tiles. It'll even make the mushroom end up on the top and not on the side. The only downside to this mega block is that you can only hit it from below.

Firstly, on the top left 2x2 box, you'll want to add wooden blocks.
On the bottom left 2x2 box, on the very left tiles, you'll want to add wooden blocks.
On the top right tile of that same 2x2 box, you'll want to add a shellmet.
On the bottom right tile of that same 2x2 box, you'll want to add a question block with a sideways spring inside.
On the bottom right 2x2 box, you'll want to add wooden blocks to every tile except for the top left tile, which will be your item.
on the top right 2x2 box, you'll want to add a one way platform, and on top of that, the right tiles of that box with sideways springs, and the left tiles with cloud platforms.

If you want the item to always go to the right, you'll need to add a sideways spring on top of the top left tile.

Mind posting here how you did it? As in, please make a text guide.