Continuing with my exploration into Twist Boxes, this time with a very unique model, the Self-Closing Origami Twist Box (original title Caja Con Autocierre). This origami box is designed by Angel Ecija Blanco. The diagram was published twice: once in the Pajarita Magazine in 1995 p. 27 and one more time in the Pajarita Magazine Extra in 2008, p. 50.
What Origami Techniques Make This Happen
This single-sheet origami box is made of a twist fold on the bottom of the box and a special V-Twist fold towards the top of the box. Angel Ecija added a clever crease in the middle of the box that is responsible to make the bottom part of the box a bit slimmer. This lets the lid slide straight onto the bottom of the box without any friction. Normally when you fold a box, you always need to make sure that the top is slightly larger than the bottom, so it slides on without distorting the bottom of the box. Additional to that, the box has a tiny square hole in the lid.
Applying the Design to Any n-sided Box
The original Self-Closing Origami Twist Box by Angel Ecija Blanco is a 4 sided box, folded from one square sheet of paper. But the design can actually be applied to any n-sided box. All you need to think of how many sides the box has and the specific angle you will need to get the closing (top & bottom) right. In previous articles (for example Origami Incense Sachet) I talked about the exact mathematics that make this magic happen in detail.
Things To Consider
First of all, the choice of paper is really important. I’ve folded this box countless times and was never really satisfied with the outcome until I tried it with Tant paper. Most papers (including Kami, Copy Paper) are either too thin or to weak to withstand the opening and closing of the finished model. The silver boxes are made from silver Stardream paper, which is a pearlescent cardstock.
Most of the times the paper wrinkles and the original creases that actually make this model work disappear or get ruined. Also while you push down the top, unsuitable paper makes the sides dent in.
Be sure to score those V-Twist folds and then, gently without damaging the structure surrounding these folds, crease them. That is actually easier said than done, as they are exactly in the middle of the paper. The more the fibres of this area are undamaged, the better the self-closing mechanism works.
4 Sided Twist Box vs 6 Sided Version
In my opinion, the 6 sided Self-Closing Origami Twist Box works slightly smoother, both when opening (pulling up) and closing (pushing down). I’ve also folded an 8 sided version of this box as a trial in copy paper, which also worked ok.
Another Similar Version of The Self-Closing Origami Twist Box
Anine Cleve Christensen discovered independently a very similar version of the 4 sided box around 2012. The folds are almost identical, except her design uses regular twist folds as the top mechanism. You can find the diagram here.