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How to fold an origami aquarium

A real project. Cut battlements into a grey castle and pleat a ledge, comb-cut four sword leaves, snip a pufferfish while it's folded in sixteen, fold an angelfish and a treasure chest, then glue it all in a framed tank with a lid that stands up.

You need: 10 pieces: 7 × 8.5 cm grey, then green, brown, tan, orange, yellow, slate, blue and half-A4 black (sizes in steps). Scissors, glue, white gel pen, black pen.. Challenge, 56 steps, about 60 minutes.

Steps

  1. Castle: fold in half. Start with the hard part, the castle: a 7 × 8.5 cm grey piece, grey side up, standing tall. Fold the left edge over onto the right edge.
  2. Castle: in half again. Fold the right edges back over onto the fold.
  3. Castle: crease a guide. Fold it in half one last time, the same way, and crease it hard.
  4. Castle: open the guide. Open that last fold again. Its crease shows where to cut.
  5. Castle: cut the battlements. Through all the layers, cut down the guide crease 1.2 cm from the top, then straight across to the right edge. Throw the little block away.
  6. Castle: open it. Unfold the last fold.
  7. Castle: open flat. Open it flat. Three square teeth stand along the top with wide gaps between them: battlements!
  8. Castle: fold up for a ledge. Fold the bottom edge up on a crease 1.7 cm below the bottom of the gaps.
  9. Castle: pleat the ledge. Fold it back down on a crease 4 mm higher. The pleat makes a stone ledge across the tower.
  10. Plant: new sheet. Set the castle aside. For the water plant, take a 3.6 × 9 cm green piece, green side up, standing tall.
  11. Plant: fold in half. Fold the left edge over onto the right edge.
  12. Plant: in half again. Fold the right edges back over onto the fold.
  13. Plant: and again. Fold it in half once more, the same way. Crease all the layers hard.
  14. Plant: cut the leaves. Cut through all layers from the left side 1.8 cm above the bottom, up to the top right corner. Then cut the outer layers again, ending 2.5 cm lower.
  15. Plant: open it. Unfold the last fold.
  16. Plant: open again. Unfold the next fold.
  17. Plant: open flat. Open it flat: four pointed sword leaves rise from the band, the outer two shorter.
  18. Chest: new sheet. Set the plant aside. For the treasure chest, take a 5 × 4 cm brown piece, brown side up, long side across.
  19. Chest: fold the top down. Fold the top edge down on a crease 1.6 cm below it.
  20. Chest: pleat the lid. Fold it back up on a crease 3 mm lower. The pleat's edge is the rim of the lid.
  21. Chest: dome the lid. Fold the two top corners behind, 1 cm each way, for a rounded lid. Fold the bottom corners behind 4 mm for little feet.
  22. Gravel: new sheet. Set the chest aside. For the gravel, take an 18.6 × 3 cm tan strip, tan side up, lying long.
  23. Gravel: fold in half. Fold the left end over onto the right end.
  24. Gravel: in half again. Fold the right edges back over onto the fold.
  25. Gravel: and again. Fold it in half once more, the same way. Crease all the layers hard.
  26. Gravel: snip the bumps. Snip a little slant off both top corners of the stack, from 3.5 mm down each side to 9 mm in along the top.
  27. Gravel: open it. Unfold the last fold.
  28. Gravel: open again. Unfold the next fold.
  29. Gravel: open flat. Open it flat: a row of eight low pebbly bumps.
  30. Build the tank floor. Glue the castle behind the gravel's left part and the plant behind its right part, feet 1.5 cm down. Glue the chest on the gravel in front, in the middle.
  31. Angelfish: new sheet. Set the floor aside. For the angelfish, take a 5 cm orange square, white side up, turned like a diamond.
  32. Angelfish: triangle. Fold the left corner over onto the right corner. The right point is the nose; the top and bottom points are the long fins.
  33. Angelfish: in half. Fold the top point down onto the bottom point.
  34. Angelfish: snip the back. Snip the corner where the two folds meet: from 7 mm along the back fold to 6 mm along the middle fold.
  35. Angelfish: open. Unfold the top half. A notch now splits the back, so the two fins sweep up and down past the tail.
  36. Angelfish: blunt the nose. Fold the nose tip behind, 5 mm.
  37. Pufferfish tail: new sheet. Set the angelfish aside. For the pufferfish's tail, take a 3 cm yellow square, yellow side up, turned like a diamond.
  38. Tail: fold in half. Fold the right corner behind onto the left corner. The folded edge is the end of the tail.
  39. Pufferfish: new sheet. Set the tail aside. For the pufferfish, take a 5.5 cm yellow square, yellow side up.
  40. Pufferfish: fold in half. Fold the top edge down to the bottom edge. The middle of the fold is the middle of the fish.
  41. Pufferfish: in half again. Fold the left edge over to the right edge, making a small square.
  42. Pufferfish: corner to corner. Fold it in half from the middle corner (top left) to the far corner, bringing the bottom edge up onto the top edge.
  43. Pufferfish: once more. Fold the slanted edge up onto the top edge, from the middle corner. Now it's a thin point of 16 layers.
  44. Pufferfish: snip the spikes. Make one snip across the wide end: from 2.6 cm along the top edge to 2 cm along the slanted edge, both measured from the point.
  45. Pufferfish: unfold. Unfold the last fold.
  46. Pufferfish: unfold again. Unfold the corner-to-corner fold.
  47. Pufferfish: and again. Unfold the left half.
  48. Pufferfish: open it flat. Unfold the top half. A round, puffed-up fish ringed with eight spikes!
  49. Lid: new sheet. Set the pufferfish aside. For the tank's lid, take a 22 × 2.7 cm slate-grey strip, grey side up, lying long.
  50. Lid: neat edge and slopes. Fold the bottom edge behind 5 mm. Fold the two top corners behind, 1.2 cm each way, so the lid slopes at the ends.
  51. Frame: new sheet. Set the lid aside. For the frame, take half an A4 sheet of black paper (21 × 14.8 cm), black side up, lying long.
  52. Frame: crease the stand. Fold each short end in 4 cm and open it again. These two creases let the tank stand up.
  53. Water: new sheet. Set the frame aside. Last, the water: an 18.6 × 11.8 cm light-blue sheet, blue side up, lying long.
  54. Water: the water line. Fold the top edge down 6 mm. The white strip is the shiny top of the water.
  55. Fill the tank. Glue the frame behind the water, 1.2 cm showing at the sides and 1.9 cm above and below. Glue on the floor, the fish and the tail, and the lid over the top edge.
  56. Stand it up. Bend both end panels gently towards you on their creases, and stand the tank up on the table.

Feeding time!

With a white gel pen, dot bubbles rising from the castle and the pufferfish. In black, draw the angelfish's stripes, the puffer's face, and the castle's door and windows.

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