## Introduction: DIN A4 Double Rhombic Pyramid (with Integrated Hinge)

The technique for creating this DIN A4 Double Rhombic Pyramid was described in my last Instructable:

https://www.instructables.com/DIN-A4-Rhombic-Dodec...

After reviewing the steps detailed there, we will discover how to hinge together a nice toy using only three sheets of paper. The integrated hinge is what makes this possible.

## Supplies

The materials required are the same as with my earlier work - - at a minimum, A4 paper and tape. A straight edge and scoring tool are recommended for making the diagonal folds. Heavyweight paper such as the 120 gsm used here, helps to make a sturdier model. And of course, any of the A series papers will work, as would any custom sized set of sheets with 1:√2 proportions.* Like my earlier efforts, there is no need for measuring tools or cutting instruments, just simple folds to full sheets of paper!

As stated above, 3 sheets of A4 paper are required for this particular exercise.

*see my Instructable: https://www.instructables.com/Dipyramids-UnMasked... for a detailed analysis of this special rectangle and the fold pattern associated with it.

## Step 1: Fold the Sheets

The fold pattern requires a total of 12 creases. I like to start with three folds which divide the sheet in 4 equal parts along the long length of the sheet. Then I make the three folds that do the same along the short length. Next, I make the two diagonal folds, corner to corner. And last, I do the four diagonals, from center of side to center of adjacent side. See photos.

## Step 2: Form and Tape

The photos illustrated here present a visual guide for finding the form, and fixing the figure using adhesive tape.

After the final piece of tape is applied, repeat to create a total of 3 of these figures.

## Step 3: Create Hinge

Hinge as shown. Remember to align carefully, and at each hinge apply tape to both sides .

Done!

Additional photos show a more elaborate assembly of the same model. It requires three additional sheets, but the technique remains the same, as does the modularity of this entire project. Like Kindergarten Blocks, and the original Lego bricks, these DIN A units keep filling space!

(Note shared hexagonal dimensions, as expressed in last 2 photos)

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