Stackable container blank, stackable container, and method for making the same

1. A container blank comprising:

a) a base having a first pair of opposed base edges and a second pair of opposed base edges;

b) end walls, each end wall foldably attached to one of said first base edges; and

c) side walls, each side wall foldably attached to one of said second base edges, wherein each of said side walls comprises:

i) an outer wall foldably attached to said second base edge along a first fold line;

ii) at least one index fold-down flap attached to said outer wall along a second fold line, each index flap having (a) a distal portion with notched or expanding extensions or (b) a border at a first angle of less than 90° from said second fold line and a distal portion with extensions therefrom, wherein said extensions have a concave curved edge at a location proximate to said distal portion and a convex curved edge at a location distal from said distal portion and

iii) an inner wall or a plurality of inner wall flaps, foldably attached to said outer wall along a third fold line, wherein said third fold line is closer to the first fold line than is the second fold line.

2. The container blank of claim 1 , wherein each of said index fold-down flaps has a border at a first angle of less than 90° from said second fold line.

3. The container blank of claim 1 , wherein said index fold-down flap has a width that decreases linearly from the second fold line to the distal portion.

4. The container blank of claim 1 , wherein each of said extensions have a first width at said location proximate to said distal portion and a second width at said location distal from said distal portion, and said second width is greater than said first width.

5. The container blank of claim 1 , wherein said extensions are covered by said inner wall or at least one of said inner wall flaps when said index fold-down flaps and said inner wall or said inner wall flap(s) are folded.

6. The container blank of claim 1 , wherein said base comprises one or more slots configured to receive a folded index tab of another container, and said slot has a width equal to or greater than a length of said second fold line.

7. The container blank of claim 1 , wherein said inner wall has a border with said index fold-down flap at a third angle with respect to said third fold line, and a sum of the first and third angles is substantially equal to 180°.

8. A stackable container comprising:

a) a base having a first pair of opposed base edges and a second pair of opposed base edges;

b) end walls, each end wall foldably attached to said first base edges at an angle of from about 80° to about 100°; and

c) side walls, each side wall foldably attached to one of said second base edges, wherein each of said side walls comprises:

i) an outer wall foldably attached to said second base edge along a first fold line at an angle of from about 90° to about 100°,

ii) at least one index tab comprising an index fold-down flap foldably attached to said outer wall along a second fold line at an angle of about 180°, each index fold-down flap having a distal portion with notched or expanding extensions therefrom, said extensions having a concave curved edge at a location proximate to said distal portion and a convex curved edge at a location distal from said distal portion, and optionally, a border at a first angle of less than 90° from said second fold line; and

iii) an inner wall or a plurality of inner wall flaps foldably attached to said outer wall along a third fold line at an angle of about 180°, said notched or expanding extension being between the inner and outer walls, and the third fold line being closer to the first fold line than is the second fold line.

9. The stackable container of claim 8 , wherein each of said notched or expanding extensions contacts a first surface of said outer wall and a first surface of either said inner wall or one of said inner wall flaps to secure said index fold-down flap in place, said first surfaces of said outer wall and said inner wall or said one of said inner wall flaps facing each other.

10. The stackable container of claim 8 , wherein each of said index fold-down flaps has a border at a first angle of less than 90° from said second fold line.

11. The stackable container of claim 8 , wherein said index fold-down flap has a width that decreases linearly from the second fold line to the distal portion.

12. The stackable container of claim 8 , wherein each of said extensions have a first width at said location proximate to said distal portion and a second width at said location distal from said distal portion, and said second width is greater than said first width.

13. The stackable container of claim 8 , wherein said base comprises one or more slots configured to receive the index tab of another container.

14. A method of making a stackable container, comprising:

a) folding two opposing end walls of a stackable container blank to form angles of about 80° to about 100° with respect to a base at a first pair of opposed edges of the base;

b) folding side walls at a second pair of opposed base edges along a first fold line to form an angle of about 90° to about 100° with respect to said base;

c) folding one or more index fold-down flaps foldably attached to an outer wall of said side wall along a second fold line at an angle of about 30°-150°, each index fold-down flap having a distal portion with notched or expanding extensions therefrom, said extensions having a concave curved edge at a location proximate to said distal portion and a convex curved edge at a location distal from said distal portion; and

d) for each of said side walls, folding an inner wall or a plurality of inner wall flaps foldably attached to said outer wall along a third fold line at an angle of about 180° with respect to said outer wall to form an index tab from the index fold-down flap, the notched or expanding extensions being between the inner and outer walls, and said third fold line being closer to the first fold line than is the second fold line.

15. The method of claim 14 , further comprising forming slots in said base at first fold line at positions corresponding to said index tabs.

16. The method of claim 14 , further comprising affixing first extension flaps foldably attached to each of said outer walls to said end walls at an angle of about 90° with respect to said outer walls, such that said first extension flaps are approximately parallel to said end walls.

17. The method of claim 14 , further comprising affixing second extension flaps foldably attached to each of said inner walls or to outermost ones of said inner wall flaps to either said end walls or to said first extension flaps at an angle of 90° with respect to said side wall, such that said second extension flaps are parallel with said first extension flaps and said end walls.