You will need
  • a sheet of paper, scissors, glue
To make the tetrahedron, we must take a sheet of heavy paper or cardboard and draw on it shown in the drawing scan. Scan size can be arbitrary. Not necessarily to copy is presented in the figure figure. In fact, the scan consists of four equilateral, equal, triangles (not counting suitable for gluing the petals).
Then you need a pair of scissors carefully cut the drawn on paper scan it and bend it on all lines. To place bend is smooth and clear, you can use any metal object. For example, the handles of the scissors. If the workpiece is cut out of cardboard or thick, quite heavy paper, the fold lines must be cut with something very sharp such as a razor blade.
After this "pattern" you have to join. Petals for gluing of faces should be placed inside the formed shape. If the cardboard was made the incisions, they should be outside of the tetrahedron.