Any size paper; card stock is best. Fold in 1/2 diagonally. Fold left tip up. Fold right tip up. Unfold.
Fold top tip down to bottom edge. Open & fold top tip down to bottom edge. Fold it back in 1/2. 3rd pic shows front & back. Holding 2 in same direction, slip one into the other. No glue required.
Make 4 of these pieces & connect them together like in previous step. Connect 1st to last forming a "ring" (Pic2). For bottom--same size square, fold in 1/2 both ways & bring points to center.
Stand the points straight up & slip into pockets of your "ring". Pockets are only on one side of ring. Take the white triangles inside ring & glue to bottom.
All done (1st 2 pics) or make it taller! Make another "ring" & push white triangles straight down. This time you will have to glue the triangles to the inside of previous ring.
Top2 pics shows box 2 "rings" high. Bottom 2 are different, but made in the same manner. This time u only make 3 pieces. Connect them together like before. This time the white triangles become bottom.
Here's examples, but u can do so much more! Make triangle box taller w/ more "rings". Make 5 pieces to connect into a ring for pentagon! U have to create a diff bottom for that one. What will u do?