Sure, a couch in Minecraft is easy, but can you actually sit in them? You can with this one! Enjoy!
Step 1: Back
To make the back of the couch, put four stairs in a row facing the front.
Step 2: Sitting Part
To make the part you sit in dog a 2X1 hole directly in front of and centered with the back.
Step 3: Mine Cart Launcher
To each side of the hole one block away, put two blocks. Then, do it again but one block higher and one block farther away. Do it again one block higher and farther away.you should now have a set of stairs. To finish it, all the way up at the top and to the side put a single block.
Step 4: Launch 'em
Put mine cart rails on the stairs we made. Then, put down slabs on top of the hole with the other slabs in it. Be sure to leave a gap between one set of slabs and the other. Finally place down the mine carts and push them down the slope. The mine carts should now be in the slabs.
Step 5: Finished
Add stairs on the side facing inwards to finish the look. To get in, hold down on the slab until you zoom in. Then jump. Now you can move around as if the slab your in doesn't exist. However when you mine out of the slab you have to do the process again to get back in.