Modular origami at its finest!

I recently learned how to use modular origami to make brightly coloured cubes and someone mentioned to me that it could be used to make Tetris-like shapes. That was all the excuse I needed to set aside a few evenings and make my own 3D set of Tetrominos!

They are a great decoration and were very satisfying to make. All you need is paper and patience :)

Step 1: What You'll Need

A total of 124 origami squares in the following colours:

18 x orange

18 x light blue

18 x purple

18 x green

18 x blue

18 x red

16 x yellow (the square Tetromino)

Feel free to use different colours, but this is what you need to be true to the game :)

Step 2: Making the Unit

To make the modular unit, follow the instructions below and reference the pictures as you go.

1. Fold the square in half and unfold again

2. Fold both sides in to the centre

3. Bring the top right corner down until it meets the opposite side

4. Bring the bottom left corner up until it meets the opposite side

5. Unfold both corners

6. Open out the left-hand side and fold in the small triangle at the top left

7. Open out the right-hand side and fold in the small triangle at the bottom right

8. Fold the left side back in to the centre

9. Fold the bottom left corner up to the middle

10. Fold the right side back in to the centre

11. Fold the top right corner in to the middle and tuck it under the left side

12. This is your basic unit!

13. This is the other side of your basic unit!

14. For corners and sides of your Tetrominos you will need to fold in one or both of the ends into the middle

15. You will see both of these shapes throughout the build, generally I churn out units and stop at stage 12. I then fold in one or both sides depending on what I need for the task at hand. (It's not fun to absent-mindedly fold up the sides and realise you needed a straight piece which now has ugly creases in it.)

After 124 of these you can do them without looking :)

NOTE: Make sure you always bring the same side down in step 3. You can fold down the left side if it's easier for you, just as long as you always do it the same way or the units won't fit together.

Step 3: Making the Tetrominos

Fitting the units together is partly a matter of common sense once you know how to make corners and edges.

To make an edge, slide the end of one unit into the side of another as shown in the picture labelled 'Edge'. Push it in snugly until the fold is flush with the side.

To make a corner, add a third unit at right angles to the previous two, sliding one edge into the side of one of the units as shown in the picture labelled 'Corner'. Once it is snugly fitted to the lower unit, take the end sticking out of the top and bend it down to slide it into the side of the third piece as shown in the next two pictures. This should give you the corner of a cube, repeat on the other sides to make a cube with an open top.

To extend the sides, join units together at 90 degrees to each other, sliding the ends into the sides. When ends poke out from the edges, fold them in and tuck them into the sides of the neighbouring units (as shown in 'Edges').

See the pictures for a few snapshots of the making of the blue piece to help you visualise where units should go and how they fit into each other. The rest of the Tetrominos are made similarly and as long as you can make edges and corners where you want them to go, making them is fairly straight-forwards.

There are a few edge-cases which we will cover in the next section.

Step 4: Tricky Parts

There are a few tricky parts worth mentioning.

The T-shaped Tetromino and the S-shaped Tetrominos (red and green) have units which need to have edges which bend both ways. In the pictures above you can see how this is done in purple. One edge is folded up on the front face of the unit instead of the back and slotted into place as usual. This happens in a few places across the shape.

The yellow square Tetromino is a bit different to the rest. The principles are the same, but it requires some dexterity to make the faces. As seen in the pictures, all four units slot together in a square shape with one straight end and one folded. Both faces of the square must go together as seen in the picture 'Correct orientation', with ends coming together at the sides. If they alternate like gears, you won't be able to put in the units between them (what I did first time round, learn from my mistakes!).

I have included a few snapshots of how the yellow square goes together as it can be hard to imagine.