I like origami. You can find all kind of uses for it. One of the first, quite easy, models I learned was the masu box. It's fast to make and very usefull.
Just a few weeks ago, I made one. When it was finished, I was looking at it and thought: "Why not try to make something else by keeping folding?"
So, I listened to myself and tried it. And I must say, the results were better then I expected them to be!
Eventually I made three different boxes/bowls kind of things.

I hope you like them!

Step 1: The Different Models

I will show you how to make the basic masu box and and the three other models

For all of these models, al you need is a sheet of squared paper and about five - ten minutes time.

Where to find:

The masu box: Step 2-5

The triangle box: Step 6

The small bowl: Step 7

The big bowl: Step 8

Step 2: The Masu Box: Let's Start Folding

Start by folding the paper in half diagonally on both diagonals. Then unfold.

Step 3: Keep Folding

Next, put the coloured side of the paper down and fold the corners to the centre.

Fold the bottom up to the centre line. Be sure to crease this line very well, this will come in handy!
Also do this with the top of the paper. Then unfold both of these folds.

Turn the paper 90 degrees and repeat the last step.

Step 4: And Folding

Take the upper corner of the centre and fold it back, so it looks like it hasn't been moved to the centre.
Also do this with the bottom corner.

Step 5: Almost Done

Now, when you are making this for the first time, this fold can be a bit tricky. I suggest you just look at the pictures, that's the easiest way to explain it.

But, for those who like explaination by text more, here it is:

You have to start with "folding in" the corners shown. Using the lines you creased, bring the two corners together so they can meet at a centre point, I've put a text note at this point for clarification.
When you have done this, fold down the corner to create one of the walls of the box and make sure the corners you folded in wont move again.

Repeat this on the other side and the masu box is done!

Step 6: The Triangle Box

Before making the masu box, fold the paper in half horizontally and vertically. This will create extra creases that will help you getting the triangle shape. You could also choose not to do this, but then the bottom of the box will be a lot less flattened.

Then make the mase box as described in step 2-5

Now fold the model in half by bringing two opposite corners to eachother.

The front sides aren't really flat now, are they? This can easily be changed by making a diagonal crease from the corner to the tops you just brought together.

That's the triangle box!

An extra style option here is to glue together the front siedes, then you could use this as a gift package :)

Step 7: The Small Bowl

Make the basic Masu box.
Make sure the double sides are up and down (noted in the pictures)
Fold these sides to the middle and flatten the box.

Fold it in half to create a sort of boat shape, the opened side should go on the outside.

When you look inside the "boat" you can see an extra layer inside it. On both sides of this layer is a triangle visible. Fold the triangle up, just enough to have it stand up straight. Then reverse the fold by folding the triangle (now it's out it's a complete side actually) even further back. You can see now the traiangle you had is now sticking out the boat. Open the bottom, put the triangle in and close again. Repeat this for the other side.

Open the bowl by pressing the two corners at the sides

So, now there is a bowl, let's make it stand!

Turn the model so the sides you just finished will be facing down.
You can see a square and four triangles. Fold the triangles so that they make the square.

Then just simply let go of the corners, turn it back over and your small bowl is finished!

Step 8: The Big Bowl

Start with making a Masu box.

Flatten it the same way as desribed in step 7:

Make sure the double sides are up and down (noted in the pictures)
Fold these sides to the middle and flatten the box.

There are notes on the pictures in this step as well.

Unfold this.

At the double sides, shown at the pictures, take the triangle and fold it back so it's standing up straight. Repeat on the other side. Reverse the fold as shown in the pictures.

Fold the small triangles as shown and then just let go of them, leave them as they are then.

That's it!